Whenever I do a ram preview, even at the lowest resolution skipping frames, it plays and loops for that instance, but as soon as I stop the playback the 'green' dissapears and it has to be cached again even if no changes where made at all to any of the composition. Purging cache and restarting do nothing.
Windows 10 Pro Build 19043 After Effects Version 22.1.1 (Build 74) GeForce RTX 2080ti 64.0 GB Ram AMD Ryzen 9 5950X
Unsatisfying standard answer: Have a look at your graphics driver and the hjardware acceleration functions. Also turn off multiframe rendering. It seems there are way too many bugs where MFR is an eager beaver and all too often invalidates existing caches, trying to re-render everything.