I don't know if this is similar issue to mine, but previously I was unable to interact with the compass on the map screen at all. This was apparently due to wrong aspect ratio setting in the display tab of the video options. It had changed (or I had accidentally changed it?) to 24:5 - Triple head. When I changed it back to it's correct setting (16:9 - Wide for me) I was able to move the compass and toggle it's size.

So, try checking your aspect ratio. Maybe?

On a second thought, as you guys can move the compass, my problem (and therefore solution) is more than likely irrelevant.