iMovie red soundbar - missing audio files
I have been moving my iMovie video clips and projects from various libraries and different drives. I now seem to have lost the link between my audio and the audio clip itself. The clip used by the project is now in an Event group called "No data" which is shown in red but the clip has no audio and has lost its duration. The audio is however shown (and is in the Project event group) but as a separate clip - and somehow not linked to the project. See screenshot below (audio clips in green above the 'lost' red clips which are linked to the project). Any ideas how to fix this / link them back? I have numerous projects like this as a result of moving the clips. (macOS High Sierra 10.13.3).
iMac (Retina 5K, 27-inch, 2017), macOS High Sierra (10.13.3)