Ken Burns effect on iMovie disappeared, what can I do?

Yes, sometimes a simple restart or relaunch will shake out glitches. Sometimes placing the clip into a different newly created project works too.

If the problem returns, try doing the delete/resetting of preferences procedure. To delete/reset preferences open iMovie while holding down the Option and Command keys and select to delete preferences in the box that appears. iMovie will open in a new empty library. Reopen your old library to get back to your projects. Possibly you may need to reboot to set the changes.  Deleting preferences is a safe procedure that will not cause data loss or disruption to your project.

Glad you were able to solve it.

-- Rich

That's not a fix, that's a bandaid! Apple must have a defect in their software. I import some photos into iMovie and the "Activity" status button shows 1/4 done. For hours! The Ken Burns effect does not work. I try to adjust where the start and end are and it limits where I can put them.