TLDR: if you can't advance the questline, go back to the Whiterun Military camp. Ride up to Dragonreach, talk to Jarl Balgruuf again. Then return to Ulfric Stormcloak.
Twitch.tv/necronomikyle
Update (12/5/18) : I've recently tried to duplicate this and it doesn't seem to work half the time. Agnostic0 gave a solution that, at least if you're on pc, works indefinitely.
Open the console and type: SetKeywordDataForLocation 16772 CWOwner 2
.Thanks again Agnostic0.
4 апр 2018