Just updated MacMini 2018 to Catalina. After upgrade, the screen resolution is aways messed up after resuming from sleep. Must restart the monitor to restore. This is a new issue caused by the upgrade.
I'm using LG 27UD58 UHD monitor via HDMI.
Eventually recabled. So one monitor hooked via USB 3.0 and one via HDMI. Seems to have fixed the issue. Would be at a loss if I was wanting to run a third monitor without resorting to an ECPU. Will be interesting to see if Apple ever get around to addressing the issue. Thanks for the input hcsitas.
Sorry for the delay. I find it strange that under “scaled” you don’t find options for resolution/frequency but a set of fonts. Can you change the setting to the other options in sequence and see if the problem changes/goes away? It’s obviously not a solution but helpful for troubleshooting. Additionally, you should update LG software, latest of which was issued only last week (long shot but can’t lose).
macOS on screen control https://www.lg.com/us/support/product/lg-27UD58-B.AUS
Meanwhile, try also for troubleshooting only:
I understand it’s a blind shoot but unfortunately I find the lack of specific resolution/frequency settings suspect on the part of LG. It’s possible Catalina’s tightened control on semi-compliant monitors which may explain why what worked before doesn’t now (happy if proven wrong). Good luck.
You'll probably see an improvement/fix with HDMI. Go ahead, make your day, recable.
Have the same issue. Have dual Dell 3K monitors and after upgrading to mac OS Catalina one monitor frequently looses its default resolution after waking the system from sleep. This is a pain because of my setup accessing the switch on the mac mini is awkward and I always put it to sleep rather than shutting it down. The system will not detect the correct resolution. The drop down list in the display settings window no longer lists the correct resolution and I have to reset the SMC, NVRAM or start in SAFE mode to try to get back the to correct screen resolution setting. This usually takes several attempts and and its not always the same reset that resolves the issue. To date it always seems to occur on the same monitor, and I haven't as yet tried exchanging cables between the two ports to see what happens. Both are connected to the USB 3.0 ports.
UrbanATB wrote:
I tried the default resolution and a few other scale sizes. All have the same problem.
What do you get if you select Default, then hold the ALT (option) key and select Scaled?
macOS screenshot please showing display settings, in particular resolution and frequency when working properly and after wake.
As a temporary workaround, in Energy settings, prevent the mini from sleeping, just turn monitors off. Then post details on your Dells. Why aren’t you using HDMI?
Thanks again for the ideas. Adjusting the Dell OSD settings had no effect. Had absolutely no issues before upgrading to Catalina. Curiously I can operate in mirror mode without problem its only in extended mode that the issue surfaces. However I have found that ensuring that the Dell monitors are manually brought out of their sleep/energy saving mode before waking the mac mini seems to overcome the problem. It is still annoying if I forget the sequence and the mac mini looses the default resolution setting. It takes multiple attempts at both NVRAM reseting and Safe mode restarts to get the mac mini to acknowledge the correct default monitor resolution again.
Can you post a snapshot of the display settings on macOS?
Neither of these suggestions helped
1) Performed the NVRAM reset, but there is basically zero positive feedback if the reset was actually performed.
2) Tried 5 different cables. One seems to work slightly better than the other, but often requires two or three attempts until the display fully wakes.
The attached image shows the issue. There are also some artifacts along the left edge of the screen.
I tried the default resolution and a few other scale sizes. All have the same problem.
Regarding LG software, are you referring to monitor firmware or MacOs driver? - I could not find either of those.
When my Mac Mini 2018 (connected via 0.50m HDMI cable) wakes up all active windows are micro sized and placed in the top left corner. Display is an HP s270n.
It would appear that Catalina could have used just a little more Q&A - and I have a suspicion that the beta tester have been more interested in getting the latest and greatest shiny MacOS than actually testing it and more importantly reporting issues
When you hover the pointer over the test below the picture of the display the resolution. I n my case on my 4K monitor I have chosen to use a resolution that appears as "2560x1440" that is the resolution that is easiest on my eyes as text becomes way to small at higher resolutions.
Mac Mini Screen resolution wrong after wake - Catalina
