messages and facetime are not working after installing Mojave

messages and facetime are no longer working after I installed Mojave. I've already closed both Mac and iPhone, and logged back in with the same username and password and no luck. I've already rebooted both and nothing. I'm hearing that this is a Mojave issue but I can't find any pointers to this from Apple on support.

Any suggestions? As I mentioned I've already logged out and back in several times to both devices and iCloud with no luck. thanks for any pointers.