iMessages not working after activating Contact Key Verification for iMessages

My iMessages are no longer working. I can send and receive text messages but cannot send or receive iMessages. All messages appear as green (when they successfully send). I believe the issue occurred after I activated Contact Key Verification for iMessages. I have since turned it off, but it has not fixed the problem. The steps I have tried to resolve: turn on and off Contact Key Verification; turn on and of iMessages; reset networks; login and out of Apple Account; fully reset my device; visited the Apple Store... I would try restore from an older back-up, but don't have a back-up available from prior to activating Contact Key Verification for the first time. Any suggestions?