To be completed by the original poster:
CMS Version
3.1.1 docker install on ubuntu 20.04.4
Player Type
android
Player Version
3-304
Issue
CMS times out when displaying media from the media library screen. Can get it to work if only show 10 entries. 25 entries usually works. 100 always times out - it will show the 100 items (mostly images) and start to pull thumbnails, but then locks up until times out. Removing thumbnail from column visibility does not help.