Video recording and playback are always in sync on my Nokia 6.
A wild guess: You record videos on an SD memory card that is too slow?
No... I always record in Phone memory and I don't have SD card in my Nokia 6... This issue started only after Upgrading to Oreo Beta and now in Official Oreo... There was no problem in Nougat it was working fine.
Which troubleshooting steps have you performed?
- Reset to default settings in the camera settings.
- Please confirm that all apps are updated in Play store.
- At least 2GB free space on the phone.
Did you receive Oreo officially over the air?
Is the audio out of sync also when the videos are played on a PC?
Maybe consider a factory 'hard' reset of the phone?
For somebody to maybe provide a better answer:
Which variant of Nokia 6 (TA-????), at which mobile operator, in what country?
Video/audio sync was fine when I tested Oreo beta, and you are the first I have seen to report sync issues in the forum. (It will probably take a couple of weeks before my mobile operator release the official Oreo).