Video exported from flash crashes every 2s

Hello, I’m new to this forum and I hope I post my problem in the correct category (if not, feel free to change it).
I’ve been using Shotcut to combine and modify raw materials from my car cameras. Lately, I’ve decided to improve my videos, by adding animations exported from flash. Videos obtained from Adobe Flash CS5 are saved in .mov format and are flawless.
Unfortunately, when I include those videos in the timeline, alongside materials from car cameras, the end effect from a file which is exported from Shoutcut looks like shown below:
Every 2-3secodns a 1-frame crash appears, which spoils the whole effect a bit.

(I could only post 1 photo - change 1 into 2 for an another example)

All the source videos (flash, cameras) are 1920 x 1080. Flash is in .mov format, camera recordings are .mp4.
The export settings are:

Resolution 1920 x 1080
FR: 25 fps
Scanmode: progressive
Deinterlacer: YADIF- temporal + spatial (best)
Interpolation: Bilinear
Parallel processing

Quality-bases VB
Quality 60%
GOP 13 frames
B frames 2
Codec threads 0

Where do I go wrong? Do I use a wrong codec (H.264) exporting from flash (Although, I used each and every possible – it makes no difference when I use it in Shotcut). Or maybe I should change something in exporting the videos in shotcut?

I’ve enclosed pictures to show the problem, if necessary, I can also post the videos to show the problem.
Hope, my problem can be solved.

tell us what codecs the files are in

ffprobe.exe -hide_banner

try remux to mkv and see if that helps

ffmpeg.exe -i -vcodec copy -acodec copy muxed.mkv

you will find both programs in the shotcut folder

I had to cut it into 4 postst because i’m not allowed to use more pics :frowning:

I’ve managed to run ffprobe (Thought I forgot how to use good old dos  )

This are the effects.
The file based on flash animation:

The file from car camera.

It should work fine as H.264 is well supported. However, the image (Frame 2 in original post) looks like some sort of data loss or decoder buffer overflow error. Maybe remux will help, but I am not very optimistic about that. Try this: open the file in Shotcut > Properties > menu button > Convert to Edit-friendly.