Edit iPhone slow-mo videos on a PC with Sony Movie Studio or DaVinci Resolve

I use Sony Movie Studio Platinium 14 and DaVinci Resolve 16 to edit videos. I recently tried to edit a slow-mo clip shot on iPhone XR and found that neither of these applications could properly open and display them. These videos were encoded with H.265 or HEVC (High Efficiency Video Coding) and shot at 240fps. This high frame rate is actually what makes them slow-mo. When played back at a normal frame rate or 30fps they appear as slow motion.

After doing a few tests with Windows software I could get my hand on (Handbrake, etc), I couldn't find anything that would allow to convert them into something editable in Movie Studio or Resolve.

DaVinci Resolve render error - Please check if the clip is still available on the drive

Issue

DaVinci Resolve 16 render task fails in with the following error:

Render Job 1 failed as the current clip could not be processed.
The clip 2020-02-28 22.55.25.MOV could not be decoded correctly.
Please check if the clip is still available on the drive.

Inaccurate timeline seeking for videos encoded with Handbrake

Issue

Videos produced with Davinci Resolve (Cineform) and encoded to H.264 MP4 with Handbrake don't work properly with some video player (i.e. Media Player Classic). The issue occurs when seeking / skipping using timeline. Instead of jumping to the place clicked on the timeline, it starts playing several seconds earlier or later.

Plex Media Player Crashes - Could not create EAE working directory

Issue

Plex Media Player (v2.54) crashes on launch and the following error message is displayed:

PMP Fatal Error!
Plex Media Player encountered a fatal error and must exit
Could not create EAE working directory.