2018 Mac Mini - monitor problems

Don't waste time on that - just bought (unfortunately) a Mac mini 2018 model and the problem was persistent with usb-c to displayport. Only HDMI-HDMI actually works. Tried to delete the disk and install Catalina fresh - same problem from the moment the installation was done - no extra software installed - pure Catalina. Either its a hardware problem persisting from 2018 launch - or macOS developers are not worth their salt. This is expensive equipment with problems with basic functions - so unlike Apple pre-Tim Cook

We know there are hardware issues that should have come out in testing, like the way it disconnects my Thunderbolt 3 port for a moment when Bluetooth is turned on. TB3 is used for an SSD so this is “bad.” 

Since mine is out of warranty and I did not Applecare it, I'm SOL.

I reported my display issues and they finger-pointed to LG then told me to wipe the drive and start over with a clean system. The answer to that is always “no.” It's obviously not my software.

My display is working fine under Mojave, I hasten to add. For me the fix was using Apple's awful 30-Hz adapter - once. It seems to have reset something in the system and now it works fine. Go figure.

Threw some more money after this Apple problem and purchased a TB3/USB-C to DP adapter instead of a cable

Used the DP cable that came with the Samsung 49" UWHD monitor and it actually works

Both as single display on DP and as dual DP + HDMI (monitor have PBP) - and works when booting, which was failing every time with the TB3 to DP cable (both as single and as dual DP + HDMI). Now it works and plays nicely

Only thing is that the display does not appear to wake until the login screen, which is weird - or slow?

The adapter I bought - randomly - was tomtoc USB-C to DisplayPort 1.4 Adapter 8K 60Hz, USB 3.1 Type-C/Thunderbolt 3 to DisplayPort Cable Slim Aluminum Shell Compatible with MacBook Pro, Ma .

It works with 100 and 120hz as well - not that I see much difference, but that's what the monitor should be running at. Apple's implementation of screen handling is horrific though and any resolution - and especially text - look like **** compared to the Win10 connected to the same monitor on DP (2xDP, 1xHDMI input). Can't recommend the Mac mini at all as it is presently - wether or not its hardware or 10.15 that is too poorly constructed.

Well, I saw this in the macOS 10.15.4 What's new.. "This update also includes bug fixes and other improvements:

• High Dynamic Range output to HDR10-compatible third-party displays and TVs connected with DisplayPort or HDMI

"

So I've updated, and guess what? No change. When connecting my 4K TV's HDMI cable directly to the the Mac mini's HDMI port, the boot up screen starts out in 4K, but then drops to 1920 x 1080 half way through the boot. If I log in, the system preferences -> displays still only lists 1920 x 1080 as the maximum resolution. HOWEVER, if I connect the TV's HDMI cable to a displayPort to HDMI adapter, the Mac mini boots in 3840 x 2160 and stays in this resolution. When logging in, preferences -> displays shows 3840 x 2160 as one of the options under the (*) Scaled windows.

NOTE: This is slightly different (and worse) from 10.15.3 in that the previous version of Cataline listed 3840 x 2160 as the "Default for display" but now, the default is 1920 x 1080 and I needed to switch to 3840 x 2160. Oh well, at least it stays in this mode through a reboot.

Steve

The key in your solution seems to be not having an LG monitor.

Negative. I don't have LG monitors and I've experienced this problem. It might be several different manufacturers, the cables used to connect the monitors, or the Mac mini itself.

Update. Deactivate Night shift. OSX charges faster and with no graphic problems, at least in my case.

Hope it works

Thanks! Will definitely check it out.

The cable just needs to be rated to run 4K@60Hz regardless of cost. Here is the one I used.

Comsol COCMDP015.

I also tried various cheaper ones from Amazon which also work well.

thanks, just ordered 60hz/4k rated, USBC-DP cable.

This mini just consumes a lot of money to keep it working.

LOL I just spent equivalent of 100 euros on various cables to get this far.

Got call but there was no real update, case under review but they acknowledged the issue is known and widespread so I hope there will be more traction soon.

Does it work with Hdmi-Usb c adapter or it's better to use a cable? Is there any difference?

@Mr. Scottish Mike,

Not a helpful answer from Apple. Call them back and escalate it. The advertising materials clearly say it works with 4K monitors, not just specific LGs.

Too scared to try Catalina, heck, I'm not even going back to verbose boots...