This happened twice on the same workbook: I protected cells (allowing
user to select but not modify cells or change data), then protected
the sheets with a password, then shared the workbook with track
changes set up. If I then select a cell that's supposed to be
protected, I can delete the data. If I unprotect a sheet in order to
view the cell formatting, all the cells I protected are now
unprotected. Anybody know what the heck is going on?

I had this happen to me:

The cells in the worksheet were unlocked somewhere in the process of
creating it and thinkig the cells were already locked, I did not check
to confirm when protecting the worksheet.

Goshute