win 7 LO 5.3.3 Calc Paste option disabled

Win 7 LO Calc 5.3.3 This happens with MS Excel formatted (.xls) spreadsheet files.
There are times when all paste options are disabled (greyed out) even when I’ve selected a blank cell.

I can copy or cut several cells from another XLS file, but I cannot paste (even with Ctl+V) the content. However, other times that works just fine - for one cell or for several, and for reasons I can’t figure out. I cannot seem to repeat it when I want to.

Is it possible that, when the problem occurs, copying and pasting just one cell fix the matter?