This may not be the issue, but its worth checking. Have you measured the latency of the screen you are using to watch the video while you edit/mix? If the screen is adding latency, you may be editing sounds to where they look in time with the picture, but are in fact off. I use the Catchin' Sync app to measure the video screen latency and determine the correct value to enter into the Pro Tools Video Sync Offset field.
https://quietart.co.nz/catchinsync/