May be a red herring, but I used an iOS app named “BLESerial nRF” to capture the NMEA output from the Postcard (see screenshot photo below).
The app offers Display Options for Separation of Incoming Messages. I chose “After newline character” as opposed to “After each message”.
It appears that a “newline character” is not being sent at the end of CGA sentences, possibly causing the RMC sentences to be missed???
