I had installed Windows 8.1 and had this problem.
Simply uninstalled and then re-installed each one and now the problem is gone.
THIS is the solution to the problem.
You have to manually delete and reinstall each and every app that doesnt't update on its own. Only Microsoft apps show this problem, all the other ones do not need to be reinstalled.
Please note that this problem is NOT related, in any way, with Avast.