Have an unprotected sheet where Column A will not show. Selecting a cell in the Name field then Format>Columns>Show does not work.
Alt-Right Arrow widens the invisible column (I can tell by seeing text in A1 move) but doesn’t show it.
Selecting the entire sheet and Format>Columns>Show does not reveal the column.
Selecting the first visible column (B) then Format>Columns>Show does not work.
I’ve closed and reopened both the sheet and LibreOffice, to no effect.
May be, the column width is very small but not completely hidden.