If you Bluetooth printer is not recognized, it helps if you can debug the device capabilities.
To do so, install the nRF Connect for Mobile app on Google Play.
Once installed, launch the app, and scan for devices. When your device is detected, tap on “CONNECT”.
Once connected, the nRF Connect for Mobile app will show the device details.
Unfold all the device capabilities by tapping on them, and send screenshots to email@example.com