Seems like there are 2 things going on here
1. A legit bug that was causing the castle story to happen sooner than it should have, causing the Campus and further missions from being unlocked (fixed now according to the patch notes)
2. (SPOILER) Players thinking that the Castle settlement is supposed to get people to resettle, and offer new quests and missions. This isnt supposed the happen. The settlement is dead, because of the attack on it. It stays grey even after doing the Jefferson mission.
If you have managed to move on in the story and unlock the Campus Settlement and missions in other zones, then the bug is fixed, and everything is working as intended.
This is something the game team are still looking in to at this time.
A workaround that some players are finding helps is to matchmake with another player who is at the exact same mission therefore completing the mission as a client in another player’s game.
I would also advise to make sure that you have completed all missions prior to the castle settlement becoming available.
That is ok. See https://support.ubi.com/en-US/Faqs/000042169
I can talk to Kelso who is still stuck down in the basement. The cutscene will play but I’m not directed to the mission. Maybe because I’ve already beat the mission? Nothing happened after I beat it the first time, and beating it again (which was insanely difficult playing solo this time for some reason), even after the patch, has not unlocked the Castle. I’ve been progressing with other side missions but how is this still happening?? I don’t want to play that ridiculously difficult mission again!!! Just give me the Castle,Ubisoft!!, please???!!!
No, it is NOT supposed to be resettled. There was a bug with being able to access it too early and then not be able to progress. A prior patch solved this. However there still is a bug that if you return to the Castle to talk with Kelso after clearing the Plaza you will get the same cutscene instead of the correct one where she says that the survivors went to the Campus and you should do the same. For some the Campus doesn't appear on the map but if you Google it you can see where it should be. Others have reported that if you go to the location the story will progress. For those that entered the Castle too early because of the mentioned bug UBI has suggested teaming up with someone that has not done it yet and complete it that way. A future patch will hopefully solve the outstanding issues.