Hi thanks @Marie and @Phil_Seeman for your help.
Just came back here to report and update.
BTW - this was happening in Excel and Google Sheets.
It happened again this morning and no amount of copying and special pasting were fixing the issue (Marie - I think the default was automatic - but I tried changing it to all kinds of different formats).
Here’s what fixed it: going from 2 decimal spaces to 0 decimal spaces (at least in Excel with this new file, fixed the whole column instantly.)
Hope you and everyone is healthy and safe.
EDIT: I spoke too soon. It turned the entries into a number, but on sorting I noticed there were a lot of duplicated #s. So something happens to the Task IDs when being converted or copying and pasting into new cells.