M1 Macbook air external display issues with usb-c

No signal at all here with a M1 Macbook Pro and a BenQ EW3270-T type EW3270U.

I tried shutdown, plug the monitor, power on but no success, tried with apple and BenQ original usb-c cables.

I reached BenQ and they told me it's an Apple issue. (I think they are right, the monitor is working A1 with my 2018 MBP and my HP laptop.

I reached Apple, at first I was told I have to pay for the thunderbolt3 2M cable at 130$cad (!!!!) Then they told me Apple knows about that issue and engineers at Apple are working on it but there is no time estimate for the resolution or any documented link available to consumers.... That is so lovely when you get such a nice machine with only 2 usb-c/tb3 ports... Somebody didn't complete their homework before putting that product on the market but still ask the big price for a supposedly pro model....

Yes I did. I tried both cables, the original LG USB-C cable and also the Apple original USB-C/Thunderbold3 one. Same behaviour.

Also nothing changed by changing Resolution or scaling down from 4K to 2k by 60 Hertz.

The monitor (LG 32UN88a) is working fine with my Windows 10 Laptop over USB-C, so I think the issue is with the Apple M1 Chip.

Thunderbolt cable supplied with LG 32UL950-W does not solve the crash after sleep issue, i.e. connection between M1 laptop and monitor when both have been put to sleep. Connection can be reestablished without crashing the laptop by turning off the monitor (rather than sleeping) after the laptop has been put to sleep. After waking M1 laptop, unplugging and then re-plugging the thunderbolt cable back into the laptop and then turning monitor back on yields a working connection. Occasionally establishes a connection without unplugging and replugging. Less than ideal work around, but when the two are communicating, thunderbolt works perfectly, including charging from the monitor.

I have a similar problem. I found this page via MacRumors.

My M1 MacBook Pro 13" is plugged into a Dell 24" HD monitor via HDMI.

The M1 didn't detect it the first day. The next day, when I woke it up, it was working, but ever since then it's not consistent.

I disabled the "Prevent computer from sleeping..." setting and that helped some but after restart, the monitor wasn't detected again. So I put it to sleep and woke it up a few times until it began working.

This is frustrating.

I'm just surprised to see how they could come up and put on the market such products without even testing... I mean, having a few guys testing external monitors on a device that only has usb-c connectors type doesn't look like a big mountain to me...

Plus no public words on this issue, no dates, no nothing...

Hey Apple, i'm not plug-in in a Nasa controller.... It's just a freaking monitor !

I understand all the blablabla regarding the fact that it's a new processor and everything but then, you delay your sales by a few weeks and you fix the **** thing !

if they can't fix it within a days I'm returning mine... Didn't paid the prime price to be a beta tester... I need a solid machine...

Hi thank you! I was aware of the option key. This was the only way to get 3440x1440 30Hz. There is no way to change Hz. This is really frustrating for consumers to be catched this way with a unstable f$%$_G high priced laptop.

I have the same problem with a BENQ PD2700u and my M1 MacBook Pro. I am using a Belkin Thunderbolt 3 Dock Pro which is connect to the monitor via display port and to the MacBook via USB-C / Thunderbolt. I tried the trick with the disconnect/close-the-macbook/connect/open-the-macbook and found the MacBook either to crash and reboot or to actually work (50:50 ratio that the MacBook then crashes after a few minutes). Very frustrated with being confronted with this kind of basic incompatibility. If this remains an issue I'll send back the Macbook as I cannot allow my IT-Setup to challenge my workflow so intensively.

What struggles me is that the same setup works perfectly fine with my older, non-4k monitor, a Dell P2421.

Hi and thanks for taking time to post this.

I just purchased the ASUS PA279CV too and am having USB-C issues too.

Initially I found that the USB-C cable (supplied and my own) would not charge my Macbook.

To test if the cable worked at all, I connected one end to the Macbook and the other end to a USB-C phone (not the monitor). Happily, the phone started to charge so I could confirm the lead was not faulty.

Only after this, could I get my M1 MacbookPro to charge from the ASUS PA279CV.

However, I could not get a video signal from My M1 to the PA279CV regardless of what I tried. HDMI worked fine BTW.

At one stage I had an alert on the Macbook telling me a USB device was drawing down signficant power.

I'm going to try a few things over the weekend. Overall, very impressed with the ASUS monitor but this seems a let down. Unsure if the issue is with Asus or Apple.

I'll have a spare Macbook Pro (15") next week and will see if that makes any difference.

Also had problems connecting my new 2020 MacBook Air M1 to an external monitor. I used an HDMI to usb-c cable to connect to my Dell monitor. The monitor did not receive any signal. When I plugged in the usb-c cable, the Mac froze for a few seconds and displayed nothing on the external monitor. I tried shutting and opening the lid, and restarting the Mac, but nothing worked. My wife's 2019 MacBook Air (Intel model) worked perfectly with the same cable and monitor.

My solution ... I bought a Belkin usb-c to VGA adapter (sold by Apple) and used a VGA cable to my monitor. It worked perfectly! Looks like M1 still has major issues with HDMI.

UPDATE: I've had my M1 for a month now and here's what I've learned.

I have an external 24" Dell HDMI monitor. The M1 wasn't recognizing it at first.

I learned that the M1 will recognize the monitor after it's been asleep. At first I thought it had to be asleep for several hours because when it first started working, it was when I'd wake it up in the morning after it was asleep all night.

If the monitor didn't work, I'd put the M1 to sleep for a few seconds, wake it up and the monitor would work. Sometimes I'd have to do this a few times to get it to work.

I had my monitor connected via an Apple dongle and I also had a non-Apple dongle which connected my external HDD and my wired keyboard. For whatever reason, the M1 didn't like having both dongles, so I paired it down to one dongle. That began working better, but it's still not perfect.

My monitor works most of the time but sometimes I still have to mess with it in order to get it working.

None of us should have to go through this much hastle to get something this simple to work. Especially with how much we pay for the M1. It's beyond me why Apple hasn't addressed it yet.

Hope that helps someone out there.

I have a similar issue with my MacBook Air M1's usb-c. I use a Plantronics external dock and headset for work and the USB for the dock plugs into an apple usb-c adapter and is sometimes recognized, with no rhyme or reason as to why. What's quite strange is I also have a Belkin adapter working with no issues at all so far plugged into the other usb-c port for my ethernet hookup. Both adapters and corresponding units work perfectly with my Dell laptop and my old Mac's thunderbolt ports and corresponding adapters. Very strange. I've tried all the shut down/sleep mode/plug in/plug out "fixes" and none of them are working for me. Once the Apple stores open back up here on the west coast I'll be returning this Mac unless I can find a fix that works reliably. Very very frustrating.

I should have listened to the reviewers on Youtube who mentioned this issue. This thing just does not detect any external monitor and I am stuck with this tiny 13" screen. I can live with the constant crashing of most applications including Apple's own applications like Logic Pro on this machine but the tiny screen makes it completely useless for me. This was a waste of money & time. The bottom line: "Do not go by Apple hype. These days they are just interested in creating noise rather than making products that actually are functional."