Excel File Reformats when Reopening

I have been using the same file for over a half a year updating data into it on a weekly basis with no problems until the past week.

When I save it (but do not close the file yet) the formatting of the pivots (about 15) stay as is. It is only after I close the file and reopen it does everything go ape sh*t.

I created a new excel today and worked for 6+ hours on duplicating the pivots and saved it. When reopening it I realized that my 6+ hrs of duplacting was thrown down the toilet.

Can someone please help me with this?

Does anyone have any solutions for this issue?

Please help.