PASTE works on some spreadsheets, but is greyed-out in others. Why?

I often have several spreadsheets loaded - the list is visible under WINDOW, & I can switch between them instantly.
Only one instance of LO is active. COPY & PASTE work fine in some sheets, in other sheets COPY seems to work [cell boundaries turn to dotted or dashed lines], but PASTE is greyed out , PASTE ONLY when selected says “no selection possible” & PASTE SPECIAL is missing!

Seems as tho some option is set-up differently between the sheets that DO & the ones that DON’T - work.

What could it be??? I can’t find any setting or option that seems relevant.

Up-dating LO recently seemed to fix this problem for a day or two - but then it returned!
Currently using V5.4.7.2.

HA! closing the non-working files, then reloading them seems to fix PASTE. Still don’t know how/why PASTE greys out!!

Make sure you don’t have some sort of Clipboard “Manager” (aka destroyer) running on your system. Many if not most of them are utterly broken.