I built a model from an online course in Lynda. When I edited a strut length, the model's joints froze.
Just run Modify/Compute All after closing the edited sketch and the joints work again.
Hope this helps!
This comment led me to the solution.
http://forums.autodesk.com/t5/design-validate-document/joints-seem-to-be-a-challenge-for-fusion-360-...
BTW: The screencast title says 'jont' instead of 'joint'. Anyone know how to fix the typo?
