There are a few missions where obvious tricks dont register. For example the philly vert challenge where you do a grind stall to kickflip or the flipflip to front air. Spent so much time retrying tho...
xjhzyx The 'Shut it Down' challenges were flagged as possible bugs and later confirmed not to be one in the bug forum. If you completed all goals in one run, it will work.
The confusion seems to come from the fact that the green checks on goals can come from multiple attempts, for example, if you did the Weddle Body Flip 180 in one, and the rest in another attempt, that isn't shutting down the challenge. All must be completed in one attempt.
As far as the Grind Stall to Flip Trick, that works fine with multiple stalls shown below; make sure you grind all the way to stall before flip tricking out. If you flip before it says stall in the bottom left that won't count.
That being said, if you have a video recording of you doing the exact same and it not registering, that would be helpful for reference, as maybe I'm not getting the same results as you.