What steps are you using to sync everything?
If the cameras and audio recorders aren’t jammed sync’d sometimes they will drift, especially over 5 hours.
You either have to sync manually, or use Plural Eyes which has a drift compensation feature, but even so, it’s not magic.
You say that all the audio is in sync, but the video is not.
If you isolate and play that clip where the video is not in sync with the audio, is it out of sync with itself? Meaning is the file not right?
Some cameras simply can’t handle that amount of sync, or use a variable frame rate which is very hard to track and keep sync in a time locked NLE.