There is a glitch on the mission Brewing Rebellion where you cannot get into Buckingham's longhouse due to Sigurd being glitched and just stands still. This stops me from progressing the main story.
Sigurd and Basim are not moving and will not open the Buckingham longhouse door which means I am unable to progress with the main quests.
Sigurd and Basim do not move and don't help you force open the door to the longhouse. I've had this glitch since launch and have not been able to progress through the main story since.