I pinpointed the issue I had to around sometime after meeting Tona in Ledecestrescire.

I'm currently playing bug free until now. I'm always looking for the bug and saving a lot, with different saves, so that if it happens again, hopefully I can just load an older save and continue playing without the bug.

This is how I fixed my game:
I quit the game to the PlayStation main menu and instead of continuing the game, I began loading the oldest save I had and checked for the bug. If everything was alright, I would load the second oldest save and so on until the bug was present. Then I quit the game again to the main menu and loaded the newest save where the bug wasn't present. If I didn't quit it, the bug would be present even in a save where it wasn't before, so it's crucial to quit the game before loading a save without the bug.

I hope this helps.

I pinpointed the issue I had to around sometime after meeting Tona in Ledecestrescire.

I'm currently playing bug free until now. I'm always looking for the bug and saving a lot, with different saves, so that if it happens again, hopefully I can just load an older save and continue playing without the bug.

This is how I fixed my game:
I quit the game to the PlayStation main menu and instead of continuing the game, I began loading the oldest save I had and checked for the bug. If everything was alright, I would load the second oldest save and so on until the bug was present. Then I quit the game again to the main menu and loaded the newest save where the bug wasn't present. If I didn't quit it, the bug would be present even in a save where it wasn't before, so it's crucial to quit the game before loading a save without the bug.

I hope this helps.

Tried everything, nothing works. Had to give up and reload a save from early on and lose about 15 hours of game. 

C'mon Ubisoft, I never had any kind of bugs with your games. This is a real let down. 

@rapidoct what do you mean with logoff? Quitting to the main menu or quitting the game?

I'm also experiencing this bug and I already filed a support ticket.
I tried every possible fix on this tread and nothing.
I'm playing on the PS4 Pro.