How to fix refresh rate Issues on Dell monitors after Sonoma update

Same - Sonoma has changed the way Thunderbolt is put to sleep and is causing issues! This is a Sonoma problem, not the display or the cable!

2023, 14" M2 Pro running Sonoma 14.1 (and hoping the update of the week may fix something!)

Display is a LG 34WK95U 34" UltraWide 5K

For years the external monitor has worked flawlessly with both an Intel i7 16" and this M2 Pro 14".

After upgrading to Sonoma, every time my mac goes to sleep, the Thunderbolt Display is not recognized. I restart and everything works as expected, but all of my desktops have been rearranged and windows moved - which is my biggest problem!

Unplugging & restarting the monitor does nothing. Using a different 40gbps thunderbolt cable does nothing. I also have a Thunderbolt 2 Dock connected to HDMI & VGA cables that has continued to work fine, but the 5k Thunderbolt 3 monitor is lost after the screens go to sleep. Only restarting the mac finds it again.

I'm using a M2 Air with a Dell 27" 2k monitor and under 14.0 I had to unplug and plug back in after reboot and it would come back on. Under 14.1 I only have to turn the monitor off and back on to get the monitor to come back. What I just noticed though is that the Logitech webcam that is plugged into the monitor USB-A port is no longer recognized no matter what I do. Apple has seriously screwed the pooch on this one.

in my case i'm using an external docking station (Diamond DS3900PD) with two displays, it's connected to my MBP with a USB-C to USB-C cable. So I will try the USB-C cable upgrade, i just ordered a 240W USB4 40Gbps cable.

It has one 4K HDMI and one 2K HDMI, only the 4k HDMI display is working after the upgrade.

Same issue here using an AOC 27G2U/BK monitor @ 2018th MBP with latest Sonoma 14.2.1

my workaround (please don’t laugh !!!):

connect the monitor by both HDMI_to_USB-C & Displayport_to_USB-C

via old Satechi USB Hub with HDMI and via old HAMA DP_to_USB-C adapter

Works fine @ 120 Hz when Power_to_USB-C is connected too.

Doesn’t work by disconnecting Power.

Doesn’t work by disconnecting HDMI or DP.

Don’t know why…

I have a Mac Mini M2 Pro. I upgraded to Sonoma when 14.1 was available. I had one Viewsonic 4K monitor, and I was using the USB-C to USB-C cable. Around then end of November, I purchased another Viewsonic 4K monitor (not exactly the same model) with a USB hub. I added a 2nd USB-C to USB-C cable and both monitors were working great, even through a reboots or restarts. Then in Jan 2024 I noticed that on booting or a reboot, the new monitor would stay black. The status light would show a connection, display nothing, then the monitor went back into power save mode. I figured out that I could cycle power on the "off" monitor and then it displayed correctly. (like after every reboot, I would have to cycle power on the monitor to get it working) I disconnected all external devices including the older monitor, but the new monitor will not display on startup or reboot using USB-C now. I moved the new monitor to the Mac Mini HDMI output and now it works correctly again on reboots. Maybe something changed in Sonoma 14.2.1.

Just had same problem, I have resolved this by bypassing hdmi and using usb-c for both monitors

Same issue here on MacBook Pro M2 with an external 4k LG monitor. It was working fine in Ventura. It is not recognized in Sonoma via USb-C. It works via HDMI. However I have two external monitors and need to use USBC for one. apple please fix this ASAP!

That’s not very helpful if you’re like me and have Apple Thunderbolt Display. The Thunderbolt cord is literally attached to the display and you can’t remove or replace it.

Everything worked flawlessly for 3 years, multiple OS updates… until the day I installed Sonoma. Issues ever since.

I have two seemingly identical Dell monitors (S2719dc) -- one purchased in 2019 and one purchased in 2020. One works and one doesn't after the upgrade. I tried switching the cables from the monitor that works to the one that doesn't, with no success. This means it's not a USB-C cable issue.

I've powered on and off the monitors. Restarted my machine multiple times.

Is there another path forward? Or do I need to wait on Apple to do a patch to the OS?

I just got a Gigabyte M32UC - a 4k 32" monitor. I hooked it up to the Thunderbolt port on my 2019 27" iMac, and I get a black screen. Fiddle with it, and I find that 60 Hz doesn't work, but 30 does at 4k, or 30, 59.88 and 119.76 work at 2560x1440.

I boot into Monterey and everything works. I boot into Windows 10 and everything works. But Sonoma is broken at 60 Hz.

It’s 100% Sonoma. Nothing is wrong with my machines. Worked flawlessly for 3.5 years as a pair. Through every update and upgrade of macOS. The very same day I upgraded to Sonoma it’s been consistent issues. I thought about downgrading from Sonoma as I use this setup for work…

Also, the nearest Apple Store is about 2 hours away from my house so that’s not an option.

I experienced similar, but even more concerning behavior. On attaching HDMI screen (from old VGA->HDMI adapter) the mac showed the new screen but the screen reported no signal. After that the Mac became unstable. PowerPoint slides showed up black and various other glitches. Then tried to use VGA->USB-C adapter, at which point the external screen showed signal, but the instability issues persisted and PPT slide show was all-black or garbled. Rebooted and after that the USB-C connection worked as expected and my corrupted presentations appeared OK again.

i think it is a bug. i also have the same problem with my macbook m1. at first, the refresh rate option was not there. i don't know what exactly made the option appear after i did two (dumb) things;

(1) i searched for the refresh rate option then clicked it, however still encountering the same problem, no refresh rate option appeared, only in the search box.

(2) i plugged the charger and entered clamshell mode (closed my laptop while being connected to the monitor), then started doing random things, afterwards i opened it back and unexpectedly it appeard when i hovered over in the display settings again.

P.S. I am using Type C to DisplayPort adapter to connect it with KOORUI 24E3 monitor (using DisplayPort)

I contacted OWC about this. I have their 4-port Thunderbolt 4, single USB 3.1 port hub. and my ViewSonic portable OLED doesn't work plugged into it using Ventura on Intel or M2MAX. They said this is a known Apple problem and they can't do anything about it.

And as for @Cougars_2010 - if I close my MBP, the directly-connected external screen image rotates 180 degrees so it is upside down.

Needless to say, I am not happy.

Interestingly enough, my third monitor started to work again...My setup:

MBP i7

3x HP VH240a Monitors

Diamond DS3900PD external docking station

Display Manager 1.10 Builder 1.17

One of the monitors is connected directly to my MBP and the other two are connected to the Diamond docking station

Couple days ago, i decided to click on the DisplayManager icon...and boom just like that my third monitor started to work.