Can't edit 1440p videos in iMovie

If the export of the iPhone video is successful that would tell us that there is something about Go Pro’s encoding process that iMovie doesn’t like. The answer would be to re-encode the Go Pro videos with a video converter like Handbrake.

— Rich

iMovie does support 4K 30 fps. I know that from personal experience. Try recording the 4K 30 fps video on your iPhone, versus the Go Pro, and see if that makes any difference.

Make sure that your iMovie 10 is updated to most current, if you have not already done so.

If the above is not applicable, or you are still having problems, try using Handbrake to re-encode the video to H.264, Mp4/AAC, even if it is already that format. You can get Handbrake here:

https://handbrake.fr/

If still no luck, try resetting your Mac's System Manager Controller. See this link for instructions:

https://support.apple.com/en-us/HT204063

If still no luck, I suggest that you call Apple Support and talk to the savvy techs there. They have the capability of remotely accessing your computer, that we cannot do here. Click on the Contact Support item in the upper right of this forum's screen and navigate to a place where you can enter your telephone number and have Apple Support call you back. Hopefully they will be able to resolve your issue.

-- Rich

Try a test clip shooting at 4K 30 fps and inserting it into a newly created project as the first clip ever inserted into the project. That would be the way to set the resolution at 4k 30 fps.

iMovie supports 4K at 30 fps but not 4k at 60 fps. It supports 1080p at 60 fps but not sure about 1440p at 60 fps. If it does not support 1440p at 60 fps then iMovie would bump it to the closest resolution that it does support, which in this case would be 1080p 60 fps. That might be what is happening here.

Also, try opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if you get the proper resolution options. Often that will cure issues with share resolution options.

-- Rich

What is the frame rate of your 1440p video clip?

-- Rich

You are most welcome. :)

-- Rich