I have a Marshall Code 50 running MCU version 1.44 and Gateway (Android version 1.5.5) on a Samsung Galaxy S9+ running the latest OS. I can bluetooth pair to the amp and play music, but can not connect to the amp to change my presets from the library.  I have reloaded the latest firmware on the amp, deleted and reinstalled the Gateway app, paired and unpaired several times.  Nothing seems to work.  I even grabbed my old Galaxy S7 Edge phone and that Gateway app on it does the same thing.  Does my amp need to be serviced for Bluetooth connectivity?