The quest should trigger upon approaching the door. Seems like the trigger is broken for you, saving an reloading won't fix that.

Have you tried earlier savegames? How about trying the save that you used the first time to initiate the quest?

I tried earlier save which is 10-15 hours behind and everything is working well, my other saves are broken. Is there really no other way to trigger that questline without me losing over 10 hours, or starting with premade character?

Sounds like the trigger got fucked by the patch, or perhaps even by the DLC itself. AFAIK there is no way to reset quest triggers like this, so sadly you'd be forced to somewhat redo those ten hours. Is the stuff you did in those ten hours game critical (e.g. levelling up to at least 34, doing missions that need to be done before starting the DLC, etc.)?

Yeah, I lost like 1/4 of story progress, tons of sidequests, a lot of fully upgraded gear and some levels. Well that is a shame then if I can't do anything about it.

Well, don't despair just yet. You can always try a re-install, which would be much faster than replaying 10-15 hours of progress. If you weren't using any mods, your saved games should be just fine; and if you were, then they should still be ok after a clean install assuming you don't have anything left over from the mods that could mess with the game. Shouldn't you have some checkpoint saves from more recently than those ten hours ago?

What do you mean by re-install? Entire game with DLCs or DLC only, because I already tried to reinstall DLC and it didn't work. I have 3 checkpoints: 2 from last story quest and 1 from Kaer Morhen after finishing the game- they are all broken.

I mean a full re-install of everything. It's kind of extreme, but it sounds like you've already done some decent troubleshooting. I don't have a better idea, I'm afraid, than starting from a fresh game install.

Interesting that you have broken saves from before the DLC should take effect. That sounds like the sort of problem that comes from badly coded mods. Were you using any game mods, by chance? If not, then...then I have no idea at all. Sorry.

Nope, never installed any mods. It's pretty interesting that saves coming from last quest or after last quest are broken, every other save before that is fine.