Password protected .xlsm format files lose password protection after opening and closing again in libreoffice calc 6.4.6.2 (x64), even if you have made no changes. Next time you open it you won’t need the password. Anyone else seen this problem? .xlsx files are o.k. as are .xls.
Yes, that looks like it. That bug description says that save and save as show the problem, which is true, but even if you just open the spreadsheet and close it again without doing anything at all, you still get the same thing happening, password protection gone. This is a serious issue so I have stopped using .xlsm and gone back to .xls