Paste function stopped working

Hello,

Today I have encountered a very weird problem which I haven't been able to resolve. The paste function in my workbook suddenly stopped functioning corretly as soon as I opened my workbook. When I press Ctrl-V to paste the contents of one cell into another, excel pastes the value (and formula if theres one) but doesn't paste the colour or borders of the copied cell.

However, holding Ctrl and dragging the cell I'd like to copy into another cell, copies the cell normally.

I tried opening excel into safe mode but the problem persists. Opening a new workbook which doesn't contain any data or formulas also did not help. I checked the Options in excel but I couldn't see anything that might indicate this behaviour.

Has anyone else encountered a similar problem?

Thank you,
Sans