I am now getting this problem on both my Windows 10 computers. Sometimes it will work and sometimes it will not. The only security software I have in common is AppGuard. Setting AppGuard to install mode does not help and It does not log that it blocks anything. I have just reinstalled WFC on a spare computer and it still does not work. The icon shows but no screens will show. It stopped working again on my main computer today and a reinstall fixed it on that one. If I monitor wfc.exe with sysinternals process monitor I get a long sequence of Thread Create, Thread Exit repeating.