Data Transfer iPhone to iPhone

I'm having difficulty transferring from iPhone 6s to new 12 via the direct phone2phone easy method. I get thru all the prompts to the point just before transfer where it is supposed to show on both screens, and then it stops and cannot be progressed beyond that. Yes the old phone is iso 14.4 and WiFi is enabled on both phones. Also there is very little data so its not a volume issue. Any ideas where I'm going wrong? Thanks