I actually play on console (planning to upgrade PC soon), but nobody on those boards has any idea what to do about this. I'm hoping someone with access to the console can identify what I might be able to do to fix it.

I have the glitch where I've completed all Thieves Guild quests (including ALL the "Restore" quests), I've gotten Nocturnal's Blessing, and then I return to the Ragged Flagon to be named Guild Master. However, as soon as I complete "Under New Management" by picking up my Guildmaster's Armor from Tonilia, Karliah disappears from the Flagon. She never returns to Nightingale Hall and the place never gets fixed up. Instead, she turns up in the final room of Snowveil Sanctum but TALKS as though she's in NG Hall. What's more, Brynjolf is stuck on "I'm busy, talk later" loop in the Flagon.

I've heard this is connected to the "Hard Answers" Dwemer Museum quest and that going back to the museum will sometimes reactivate the quest and completing it will fix everything. However, even though I do have Gallus's journal in my inventory and it's marked as an undroppable quest item, nothing happens when I go back into the museum or into Calcelmo's lab.

I've tried every way of resetting any of these things that I can possibly think of. Using the upgraded NG Hall as home base was one of the things I was looking most forward to in the whole game. I'm really bummed about this and seriously thinking of just putting the game down. If anyone has any advice/help to offer at all, I'd be super grateful.

Advice, let it go, it's broken and you are one of the few that actually took notice. It will eventually be fixed by someone, probably not bethesda, they don't really fix their games once they walk off with your money.

Ive found so many people who have this problem, and no clear solution.

Out of all the factions i had been associated with and titles i received, the nightingales had excited me the most. I really hope bethesda helps out the lost because i was really looking forward to seeing nightingale hall refurbished and speaking to Karliah again other than at snowveil.

Being on pc i was hoping that perhaps there would be a console command to help but my search has proven fruitless.