Importing photos from Photos.app to iMovie app produces question marks
I am using an mac Mini M2 pro with both the Photos app and the Movie Library on an external SSD.
I am trying to import photos into iMovie. All my photos appear correctly in the iMovie media browser. But if I drag a photo to the timeline several things may happen. Often the image disappears while dragging. Sometimes it stays, but then later it changes into a question mark. Occasionally I have seen the progress circle active with "importing photos", but without success. Usually some photos are visible on the timeline, while others are question marks. In one case I was even able to export a project with 3 photos successfully. But after closing and reopening iMovie, all photos that were previously visible have become question marks again.
I have a lot of experience with this in previous version of iMovie/Macos, but in Ventura 13.5 and iMovie 10.3.8 this feature seems utterly broken. Or could I be doing something wrong?
Mac mini (M2 Pro, 2023)