This sounds dumb, but have you tried closing and re-opening it with m?

I too go around with my map open all the time. If you open the map from a quest objective, it will only show that quest objective and will not update. Click another quest objective, it will only show that one. If you close it and open it with m however it will show all currently tracked quests and fates.

And I could be misremembering but I think if you mov ethe area of the map you're looking at via mouse-dragging it (not the window, but the map within the window) around, it will stop updating. Or at least it stops auto-following you. So whenever I've dragged it to look at something or see where a quest is I always close and re-open it to get it back to auto-following me and updating everything.

On the other hand if even when closing and reopening the map isn't updating fates and things then yeah it does sound like a bug unfortunately.