Can't send messages via Mac

I am unable to send some messages via my Mac. It appears to fail when I'm sending to people without iMessage. This worked about a week ago.

I have reviewed this doc and I am still having issues - Use Messages on your iPhone, iPad, or iPod touch - Apple Support

Messages on my Mac are setup as follows:

I have them setup to send from phone number and email address

I keep getting the 'Not Delivered' error message.

I am connected to Wifi on my Mac and cell phone (iPhone).