I was playing through the Thieves Guild questline and then immediately encountered the cutscene with Trinity Restored. After the cutscene, I could not talk to anyone, as in the button to talk to them does not appear and clicking the button to talk won't do anything.

I isolated the problem to just the cutscene. Even after entering the Nightingale Hall, I could talk to people. I did not use any console commands other than coc Riverwood to isolate the problem. I used no exploits. My mods have nothing to do with it as the same thing happened when I turned off all of my mods.