FCPX Requiring Re Render every time I open the library

Every time I open an old library/project (editing completed), the dotted line showing need to render shows for the entire timeline. If I turn off background rendering, it is too slow and choppy to process. This is true for every project/libary on this particular external drive (WD 5TB Mac OS Ext Jour) drive. I had been approaching capacity on that disk, then deleted about six FCPX libraries to free up space (now have 2.6TB avail). MP4 and MOV files on that same drive all function normally, so it doesn't appear to be the drive. Just the drive/FCPX combination. I have opened other old libraries on another disk (WD w/ same confirmation and formatting) and they work fine in FCPX. 

MacBook 16" 2021
M1 Pro
Mac OS Monterey v12.4
FCPX 10.6.2
All updates are current

See this thread and other linked threads in that. 

fcp.co/forum/4-final-cut-pro-x-fcpx/3686...ing-not-saved#120609