When I open one of my spreadsheets, one of the sheets is protected against changes. However, I have never made such a setting, but believe it occurred after Calc and the document crashed. Since then, the document has crashed many times.
From now on, I will refer to the protected sheet simply as the sheet.
(1) I have searched through all the documentation several times, but I have not yet found a solution to the problem.
(2) I have unchecked protected in the settings on the Cell Protection tab for all cells on the sheet, which has not helped.
(3) The sheet is not locked, nor is any other sheet in the document.
(4) There is no lock on the tab in front of the name of the sheet, or any other sheet in the document.
(5) The file content.xml does not contain the string table:protected=”yes" or any other string related to content protection.
(6) I have spent a lot(?) more than 20 hours trying to find a solution and am starting to think that I will have to create a completely new document. But I am hesitant to do so, as it took me a few(?) / several(?) / many(?) hundreds of hours to create it. But sometimes you don’t have any choses…
(7) Version Information (from the About LibreOffice dialog)
Version: 25.8.4.2 (X86_64)
Build: 290daaa01b999472f0c7a3890…
(290daaa01b999472f0c7a3890eb6a550fd74c6df)
Environment: CPU threads: 4; OS macOS 11.7.10
User Interface: UI render: Skia/Raster; VCL: osx
Locale: sv-Se (sv_SE.UTF-8); UI: en-US
Misc: Calc: threaded
(8) A completely different question:
I have had problems reading large content.xml files. I have tried:
- LibreOffice Writer
- less
- Notes (Apple)
- Text Editor - Apple
- and others.
I would appreciate any suggestions for a program that can read and search content.xml files up to 150 MB in size without problem. My biggest one, so far has been something lika 130-135 MB 
I have now been using LibreOffice, mostly Calc, for a few months and I have really enjoyed it. With a few minor exceptions, it is a perfect program and extremely capable.
Thanks in advance
eRiket