I've checked the MIDI commands on the "USB MIDI Monitor" app, and my controller is sending everything correctly: channel 10, note on (48 to 51) with enough speed (80 to 127) and then it's immediately followed by a note off, just like the MIDI specification requirements.
Other Android synths are working correctly (Fluid synth for example), It's just a FL Studio problem
I can reproduce this behavior on Android 7, 8, 8.1 and 9
I also noticed that maybe FLM is not using the native android MIDI implementation(?) because some MIDI bridge apps I use cannot see FLM at all.
If you guys could use the native Android MIDI that would be great

Thanks.