I have inherited a series of 23 forms that were created about four years ago.
Each form is a multi-page table. I have been trying to revise these forms
this week, and some cells of some of the tables are suddenly being formatted
as hidden text. It isn't always the entire cell. Sometimes only a few words
or a punctuation mark will go to hidden text. Sometimes, it's an empty cell
that is formatted as hidden. In one case, the hidden attribute started
showing up as I typed.

Some earlier versions of these forms also had hidden text, but the amount of
hidden text is greater now than it was before.

I don't ithink/i it is a "copy and paste" problem or a "paste
formatting" problem. Is there any known bug that could cause text to just
suddenly become hidden?