I've found that when switching GPS providers from an external source to Integrated on iOS, the current location shown on the map freezes on the last external GPS location unless the external device is turned off or Bluetooth is disconnected before switching providers.
We've been having various Field Maps/Trimble issues and I discovered this trying to replicate other issues. I can start with the integrated receiver, connect to an external receiver (Trimble R2) via Bluetooth and switch over to that in FM without a problem. If I try to switch back to Integrated without first disconnecting the external receiver, the map either freezes up entirely, or just the blue-dot location indicator stays stuck on the previous external position.
Is this a known bug? Seems we should be able to seamlessly switch GPS providers without glitching.