This has happened to me a couple of times in the various Technical Preview updates where the start menu stop working.
It turns out a simple powershell command will rebuild the appcache to resolve
Run this in Powershell as admin
Get-appxpackage -all *shellexperience* -packagetype bundle |% {add-appxpackage -register -disabledevelopmentmode ($_.installlocation + “\appxmetadata\appxbundlemanifest.xml”)}