A co-worker is having this difficulty. Final Cut Pro X was working fine earlier but now, on Import, the Desktop and her Home folder (listed under Favorites) simply show a circular, spinning effect that never stops. The 'X' next to them have no effect. There seems to be no way of eliminating those two listings as Favorites either. We tried running X under another login but the difficulty was the same. Used Preference Manager to delete preferences but no difference. I found no camera archives on her desktop. There maybe could be a camera archive somewhere a few folders deep under her Home listing but that would mean much of the whole computer.
The Users folder was not visible in the root directory of the boot drive!
It was there, though, which allowed her to operate normally, but when she followed the directions posted to fix invisible folders in the new 10.9.3 update (even though she hasn't updated yet) it make her Users folder visible and X was able to import normally. No greyed out listings in the Favorites area of the Import dialog.