I've had this problem lately. On longer sessions Gopro splits the video to multiple files and Racechrono syncs these back together again. So if I make sure the first video file is synced correctly (using GPS data) the following "link after..." video files should be synced too? But they are not. There's a glitch and the sync goes off a second or so.
Here's a short video showing at about ten seconds in what it looks like going from the first to the second video file.
Can this problem be dependent on if I set the Gopro (Hero 7 Black) to HEVC or not?