It is getting a little more complicated Steve.
I can confirm what you have found in a roundabout way.
Initially I was opening the file from the File/Open File menu or the Open File icon on the toolbar which brought up the Windows File Explorer window where I chose the file and clicked on the open button. Once I had the file in the Playlist adding it to the timeline caused an immediate crash. Doing the same thing again but adding it from the preview window caused a crash.
Watching your video (thank you), I see that you dragged and dropped the file onto the playlist.
So I opened Windows File Explorer and then dragged the file from there and dropped it on the playlist.
I now get the same result you did, dragging from the playlist to the timeline is ok, dragging fom the preview window crashes the program.
Opening the .mp4 version of the file from the File menu or Open File icon does not cause a problem. It can be dragged from the playlist or preview window and dropped on the timeline without a problem, drag and drop from Windows File Explorer is also fine.
It just seems to be a combination of .mov file, opening within windows file explorer and the playlist/preview window.
I also think there maybe an issue with the rotation of .mov files from the iPhone that could be upsetting Shotcut. When .mov files are loaded on the windows pc I am sure their native format is landscape mode(people on their side as in the video I sent).
I use ACDSee to catalogue images/videos and the videos are always shown as landscape thumbnails but the program rotates them automatically when they play. Similarly Openshot loads the file in landscape mode in the playlist and preview window and once it is in the timeline you then have to rotate it manually to the vertical. All other windows software I have automatically rotates the file in both thumbnails and play back.
When I get time tomorrow I will take a small video with the iPad in portrait mode and see if it shows the same problem as the iPhone videos. The iPhone belongs to my daughter so I don't have access to it or know much about it, she just uploads the images to my iPad and then I put them on the pc to sort them out for her.
Thanks for you time.