Post moved!
Have you covered the basic steps?
0.) Using any mods, or have you ever used any in the past?
1.) Verify the game through GOG / Steam / Origin.
2.) Reload to a point before that quest appears in your journal and try again. Most of the bugs or glitches that remain in the game will need to be worked around this way. If experiencing an issue with a quest, avoid fast traveling. Just Roach it to the locations and ensure you hit all the parts of the quest along the way.
3.) Ensure that you have any purchased DLC and ALL of the Free DLC installed, even if you're not intending to use their features. The game requires that the all of the data be present. (People that do not have all of the 16 Free DLC installed will often hit random glitches.)
4.) If using unlimited FPS, try capping them to 60 then 30. Switch Vsync on. Sometimes, game functions are set to frame timing. Having FPS too high might cause the game to fall out of sync.
