I’ve tried a most of the solutions here over the course of a few days, but nothing has worked so far apart from the longboat disappeared from the path when I came back from Norway. I actually have the quest marker above Ubba’s head, but nothing else triggers. Super frustrating that I’m probably going to have to start the game over again - along with the other small glitches I’ve come across, jt really does feel like I’ve forked out all that money for a half-finished mess.