iMovie Taking too Long to "Import File"

I am trying to make a short movie with stills from Photos after loading a few iMovie freezes and appears to be load a file. New additions are no more than thumbnail images. This task doesn’t complete even after days you can't close the app because you get the message: "iMovie must complete other tasks before performing this operation. Try again once these tasks have been completed. You can view their progress by clicking the Activity Indicator in the toolbar."

The activity icon is perpetually on half done.

I had to force quit the app to move things on. Please help!