sent iMessages not syncing between iPhone and iPad
I am logged into my iPhone and iPad with the same appleid and I am able to receive iMessages on both devices. However, when I send a message from either, it does not sync to the other. When I delete a message from one, it does not delete from the other. I have logged my iPad into my wife's appleid and things sync perfectly, which implies that the issue is with my phone. However, I have just gotten a new phone and built it up from scratch rather than from backup and I still have the same problem. Before switching to this phone, I cleared and rebuilt the previous phone from scratch and it didn't help. I have updated all software on both my iPad and iPhone 6s to iOS 9.0.2 and the problem persists. Finally, everything used to work just fine up until about 2 months ago. Any ideas on where to look next? Help!
iPhone 6s, iOS 9.0.2, Also iPad Air 2 with iOS 9.0.2