iMovie downgrade 60fps video to 30 fps (both in project and on export file)
I have made videos in 4K 60fps using iPhone XS Max, both in HEVC using the native camera app and using FiLMiC Pro. When I import the videos into iMovie on my MacBook Pro and tap the information "i" regarding my project, it always say "4K" not "4K 60", and when exporting the file it only gives "4K" as an option for resolution, not "4K 60fps". When checking the exported file in QuckTime it says FPS: 29.97. iMovie has somewhere downgraded the video FPS.
What am I doing wrong? (I have of course made sure there are no other frame rates/resolutions in the beginning of/or in the projects - I've made them 100% 60 fps to make sure for this experiment)
Is it possible my MacBook can't edit 60 fps in iMovie? I'm running on Mojave 10.14.5 on a MacBook Pro Retina 11.1 (late 2013), 2,8 GHz Dual Core Intel i7, Turbo Boost up to 3,3 GHz, 16 GB RAM, 1 TB SSD.
Any suggestions are greatly appreciated!
(On a side note, even in the iMovie iOS app the "save to Files" downgrade 4K videos to 1080p, only when I save to camera roll I get 4K, sounds fishy too)
MacBook Pro Retina