devtrackers.gg
For those who are still looking for a solution, as Ubisoft just elegantly announced that they won't ever fix this, there will be no more updates to the game.
At the beginning of the Tomb, there is a locked door where you should leave once you finished. They patched out most of the glitches where you can brake the lock from the outside ( I don't know if the top-bottom-middle 3 explosive shot still works or not, it didn't work for me ), but you can still do it one way.
You need to equip a 2-piece Taranis armor with no weapons in hand, fire an explosive shot to the lock, and just simply punch it. The arrow will explode, and the lock will be broken. I know it's not the most convenient, you must wait for the taranis armors to appear at Reda or as a weekly item, or buy the armor set, but at least it's a solution for the completionists as myself, and at least it's not impossible to complete the game in it's broken state.
(Lesson learned from this incident: please use the manual save frequently xd)