My display is 1920x1080. Not sure if using a 4K display makes a difference.
A couple of things to try:
Reset to default settings.
- Quit Plex Desktop for Windows
- Navigate to
%LOCALAPPDATA%\Plex. - Rename
plex.initoplex.ini.bak. - Launch Plex Desktop for Windows
You’ll have to login again, configure settings, etc. If it does not help, you can restore the original plex.ini to return to your original settings.
Try previous version
Plex stores previous versions in %LOCALAPPDATA%\Plex\cache\updates.
To stop auto-updates, see In the Plex For Windows client, how can we tell if we're running the current version? - #3 by FordGuy61.