Hey Everyone,
I found a different solution that worked for me so hopefully this helps someone else out! I was having this issue as well but it was intermittent and some of the solutions here seemed to resolve the problem. After upgrading to Sonoma 14.4.1, the issue came back with a vengeance.
I have an LG 45" UltraGear™ OLED Curved Monitor model 45GR95QE-B and am using a USB-C hub that has a display port connector since the HDMI connection wouldn't allow for 120hz or 144hz a while back when I tried.
After trying some of the solutions mentioned here, the issue still persisted, but it seems that I was able to change my display port input type on my monitor itself from 1.4 (DSC) to just 1.4. This resolved the issue for me so hopefully this will help someone else out as it's one of the MOST frustrating issues to deal with. Nothing like trying to look at your computer screen only to have the picture go out randomly.....
Seems like it might have had something to do with the latest fix Apple applied for external monitors not being detected as I wasn't experiencing after deleting duplicate color profiles before updating my OS.
Good luck everyone!
<3