It seems that I am stuck on the main quest line and I can't find a way out of this glitch. I am currently on two quest that seem to conflict with each other, Joining the Stormcloaks and Season Unending. At this point in Season Unending I have to talk to Ulfric Stormcloak but he will not talk to me because I have not completed the quest Joining the Stormcloaks. Joining the Stormcloaks is suppose to be turned into Galmar but he will not talk to me because I was trying to talk Ulfric Stormcloak into talking to the Impire. I don't know what to do so that I can move on. Anyone having the same problem or have any ideas of what I should do?

I'm having this exact same problem, playing on PC.
This is really disappointing.
I can't continue the main quest.

I sent an email to Bethesda about it. They said to go back and make sure I didn't miss anything. Hell, I have gone and done ever quest in my log except the ones that it won't let me do. I replied with that and they said go back to a previous save, that is BS because I have spent another 20-30 hours on the game since then.