FaceTime not working for most contacts on 2012 MacBook Pro
Facetime stopped working on my 2012 MacBook pro for all but ONE contact (I have no issue at all using my iPhone or iPad - so all contact's info is fine). As my Apple ID is associated with Yahoo mail, I'm wondering if it is an issue with Yahoo's requirement for a '3rd party app password' to access email? I just spent about an hour with an Apple rep, who was unable to solve the mystery. Among many other steps, we 'cleared' the keychain (which deleted access to my email accounts.. since re-established.)
My OS is Catalina 10.15.8
Any help solving this is appreciated!!
MacBook Pro 15″, macOS 10.15