I have code that works fine on my Google Pixel 4a. I purchased a cheap Acer tablet and that fails to see any devices including using code samples such as MidiScope etc. Interestingly “Midi” is not selectable under the USB options. I was close to returning this tablet but an app “SimplyPiano” which I downloaded, successfully identifies my attached keyboard and is happy to use it. Any insights? (I have also tested using the Develop branch). Both Pixel and tablet are on Android 13.
So it turns out that android.software.midi (FEATURE_MIDI) is simply missing. The “SimplyPiano” app must have packaged their own to cater for the lowest common denominator.
In JUCE code this manifests this as “if (jobject dm = deviceManager.get())” returning NULL and hence a empty array of devices. Perhaps a jassert would help. Indeed the getSystemAvailableFeatures() Java function showed that the android.software.midi feature was missing. I will close this (if I can work out how) and return the tablet!