Transfer of Photos Album Contents into iMovie (Big Sur)

The help menu does contain instructions on how to import Photos and video clips from the Photos app into iMovie. It says to import the clips from the Photos item in the iMovie media sidebar, as I suggested in my previous post.

https://help.apple.com/imovie/mac/10.1/#/mov865570171

Since that procedure is unsuccessful for you, then something is not working right. I have seen the problem you are experiencing reported here a few times. I don't know whether it is indigenous to the software, thus a developer issue, or whether it is related to a confluence of other issues specific to particular formats, software versions, the device on which the clip was recorded, or the Mac setup itself.

Have you tried doing a File/Export as Original from the Photos app to your desktop, and from there dragging the clip into iMovie? Have you tried dragging the clip from the Photos library directly into an iMovie timeline?

When you import to your desktop, does the whole clip come in and play correctly? Was the clip recorded on your iPhone or some other device? What is the clip format -- HEVC, HDR, other? What iMovie version are you using?

If further attempts to get a good import are unsuccessful you might try contacting Apple Support, because they have the capability of remotely accessing your computer. The techs there might be able to isolate the problem. Click on the Contact Support item in the upper right hand corner of this forum's screen and navigate to a place where you can enter your phone number.

-- Rich

Try using the Photos item in the iMovie media sidebar to import the individual video into iMovie -- not the whole album. That usually solves the video still image import problem.

-- Rich

So I can refresh my memory, could you post the link to the previous thread where your issue was discussed?

-- Rich