since recent update I'm no longer able to use videos in premiere clip - they appear as a grey box in the clips section once imported and only the sound plays when viewing the created movie. I am trying to use mov files created out of iMovie and have tried importing them from both my camera roll and via putting them in my creative cloud folder on my Mac.
Before you updated did the same files created in iMovie work in Clip? Do these same files play correctly in the iOS Photo's app? If yes, can you please upload a sample file I can look at? If the files are not playing back properly in the Photo's app I'd suggest changing your export settings in iMovie to a iOS friendly format. Sorry I can't think of a quick fix solution right now but hopefully looking at the file will help.
Two things you could try that sometimes help resolve unknown issues:
1. Log out of the current CC account, close Clip and re-launch and sign back in.
2. Uninstall Clip from device, then re-install and log-in,