confused about hidden cells

I have received a spreadsheet, which I've opened as a .xlsx and then
saved as a .ods. It has some hidden rows that I'd like to be able to
see. So I selected the entire sheet and went to the Format/Rows menu
but the Show menu item is greyed out. How can I unhide the hidden rows?

I note that a lot of the spreadsheet is protected cells. Does that have
something to do with it? (and if so what? :slight_smile:

I'm running LO 6.2.6.2 on openSUSE Leap 15.0

TIA, Dave

Ah never mind. Immediately after writing this, I discovered
Tools/Protect Sheet and it was checked! After unchecking it, I'm fine.