I am also having the same problem on 2 different install of Project 16. Coincidentally around the same time frame I have a problem with Windows 10 Start Menu, and the windows tiles. It seem that when I add a new program tile it some how does not get indexed properly, so the start menu and Cortina both stop working. The only solution is to add a new user and rebuild all of the tiles. Microsoft is aware of the problem but like our Project problem not time frame for repair has been published.