I guess one of us who is seeing video ahead of audio needs to start from scratch, e.g. starting with TV apps only then adding external sources, and see at what point the sync issues appear.
I would think my setup is quite different from most as I have to cater for headphones as well as speakers. I have the external sources fed through a HDMI switch into the TV, then from there via optical to the processor box for Sony HW700DS headphones, then from there by optical into a sound bar. The sync adjustment for the headphones and sound bar are in different increments so it's also a challenge to get those two in sync with each other and not have an echo.