Union Depository/The Big One bugged out and I don't know what's causing it.
It's simple, I steal the truck and when I get to the bay I'm just frozen there, the guard doesn't come, the other truck also just stops, and I can't do anything except kill myself and try again. After deliberately failing 3 times so I can skip the part, the game just enters an endless loading screen and I have to kill the process. At first I though it was Rippler's Realism which caused it, but after painstakingly removing it from my mods folder it still happened. Apart from that I have a vehicle handing mod but I can't remember which one it is anymore, and of course half a dozen scripts. Could they be causing it?
They could. Try to remove them one by one to identify the culprit.
A rule of thumb - the more complex a mod is, the more likely it is that it will cause an unexpected behavior.
For example, you can run "Vigilante Missions" mod in practically any conceivable circumstance (even on missions, and even while running gameplay mods!). Yet again, install "Online Interiors (Doomsday Heist)" and you'll get an on-mission crash 90% of the time.
Keep taking the mods out for starters. Then we'll see.
@NikoTheGopnik Try just renaming dinput8.dll to 1dinput8.dll so you can complete the mission vanilla style, then rename dinput8.dll to get your mods loaded back up. Hopefully that would get you past the mission and past the loading screen you get stuck on.