Insert-Subtotals makes Column Outlines disappear

I have never noticed this happening before, but I have a few
spreadsheets with columns grouped, and when I insert subtotals the
groupings disappear and I have to go back and manually add them again.

Same thing when I remove subtotals, the groupings disappear again.

Are there any solutions for this?

Anyone have any ideas on how to fix this problem?
tia