By the way, the original files were MTS files from a camera. I could never play these files correctly. That is why I converted them to mp4, keepeng more or less the same video quality. And, at first, mp4 files played correctly.
Then I installed VP to edit the videos.
The out of sync problem happens only with the highest quality videos (10000 kbps, 59 fps). With lower quality (8000 kbps, 29 fps), it plays OK