The only weird thing in my Facebook settings is under 'Notifications'.  The 'Activity that Involves You' box is greyed out (but appears to be set to 'on'). It's annoying to have to click on the little globe in the upper right-hand corner to see if anyone responded to a post.
Suddenly stopped getting Facebook notifications in Gmail account. Notifications setting is on, and there are no Gmail blocks or filters
gmail;facebook;notifications