row height no longer automatically expanding

A few days ago, the row height in a spreadsheet stopped expanding automatically to display wrapped contents of cells. I’ve tried selecting the entire spreadsheet. Using the optimal row height command (I have not changed the default value of 0), turning off the default value checkbox will then expand row height automatically. Clicking the command a second time, I find that the default value checkbox is re-checked. Saving, exiting LibreOffice, then re-opening the spreadsheet, row height collapsed again.

In the Row Height command, default value has been unchecked throughout.

What else can I try?