Shortcut to edit cell in excel for mac (Ctrl-U) doesn't always work

Hi, I am a windows user and just recently moved to mac.

I'm using Excel for mac, and I know that the F2 equivalent (editing the cell) is Ctrl-U in mac.

I am also told that F2 in excel for mac cuts text from active cell.

The problem is that sometimes Ctrl-U works (cell edit), but sometimes it doesn't do anything.

Instead, F2 always works (cell edit), just like windows. Is this normal?

I have never seen F2 working as cutting text, as intended for mac.

I can just stick to F2 to get the job done, but something doesn't look right.

What may be the problem??