Imovie 10.1.9 clips turn solid black in Final Cut Pro X 10.3.4 after "Send Movie To Final Cut Pro"

Question

Better describe "steps to reproduce", than wrote bunch of text.

What has been made:

1. Clips has been captured by iPhone 8 Plus with 4K and 60fps.
2. Clips has been added to iMovie project from Photos.app library.
3. Clips has been trimmed and rearranged in iMovie.
4. Sound has been added as a separated track from .mp3 file.

5. Menu button "File/Send Movie To Final Cut Pro" has been pressed.
6. Imovie project has been successfully transferred without warnings.
7. All clips video, graphic parts turn to solid black.
8. Sound plays with no problems screen shows solid black rectangle.

What has been tried to solve problem:

1. Preferences restoration to default for iMovie.
2. Preferences restoration to default for Final Cut Pro X.
3. Library has been trashed and new one was created for iMovie.
4. Library has been trashed and new one was created for Final Cut Pro X.
5. Videofiles from another source (YouTube) has been tried.
6. Another projects has been created.

Suffering through with no luck. Looking for help.

Answer 1

Sorry for panic. Answer has been found.

Problem: Final Cut Pro X was unable to see 4k 60fps videos captured by iOS devices.

Reason: Unknown.

Solution: Need to update Final Cut Pro X to 10.4.1 version.

Source: https://support.apple.com/en-us/HT208131