Protected sheets lose same data - from the same rows and columns

Running LO Version: 7.6.6.3 (X86_64) OS: Windows 11.0
Build 22631; UI render: Skia/Raster; VCL: win Calc: CL threaded

i have 12 sheets- one for each month with the same layout and formatting.
I use this for my monthly financial needs (banking, bill paying etc)
After the 12 there are 3 sheets I use to forecast credit card and loan payoffs.
At the end of each month I protect each sheet completely (no permissions)
Today working on the forecast sheet I went to the current month sheet and found
A1:C13 completely blank (no data no formating) I checked the first 4 months of sheets and the same area of the sheets were missing. These sheets are protected. How did the data disappear?

This has happened in a previous version of calc and there I lost entire sheets (totally blank) that were also protected.

Maybe in relation with
Copying to Multiple Sheets
also works for deleting cells on several sheets at the same time, I have verified that it does not work with protected sheets.

Never used copy to multiple sheets nor delete on several sheets and never for the above mentions cells…

Maybe, but deleted ranges are the same in all the sheets with the issue?

Correct. (and by ranges - they are not named)…

So impossible to know what happened.
The only one with access to the file?
Are you able to reproduce the issue?, e.g., selecting several sheets without unprotected them, and trying to delete some range of cells.

Yes I am the only user of this computer and its files.
No I am not able to reproduce the issue.
Tried your suggestion and LO calc gave a warning about unable to change protected cells.

Q: Do you know anything about the file structure of calc in RAM?
Could there be pointer overruns?

What LibreOffice version did you have before? Possibly, tdf#150307 or tdf#132057 both fixed now.

Might be worth starting a fresh spreadsheet in case the behaviour is locked into an older file or template.

Previously used LibreOffice_7.5.2_Win_x86-64 when a similar senario occured- only several of the protected pages were completely blank upon opening the file. I had to rebuild everything from scratch. 6 months is data gone. (The current issue only occured while the file was already opened.)

After reading the 2 tdf’s you mentioned, neither seem to be related to my problem.