Actually, the text hasn't gone anywhere, but it just becomes invisible or
turns into a row of XXXXs when you leave the cell. Clicking in the cell
makes it visible again--but only until you leave.

I've found a lot of threads that discuss various aspects and manifestations
of the problem. Many people think it is related to text wrapping, but I'm
not sure about that. I am sure that it is not related to the size of the
text. At least not directly. Many of the threads suggested various
workarounds that are supposed to make it go away, but I've tried a bunch of
them, and no joy.

Microsoft "support" website was useless, as usual.

Anyone able to explain what's going on here? Yet another fix?