Yamaha DGX-670 with Cubasis?

I have Cubasis 3.8.5 installed on an Amazon Fire MAX.

When I plug in my Yamaha DGX-670 the audio over USB portion works with Cubasis, but the two ‘portastudio’ MIDI ports over USB are not there. When connecting the device Android asks for permission to connect the the MIDI hub and such and seems to do so, but for some reason it’s not registering properly?

I’ve tried both, plugging in the piano and then starting Cubasis, and waiting until after Cubasis is launched to plug it in.

Other notes:
n-Track Studio can send and receive MIDI from the DGX piano. If I plug in the device first, it uses system device drivers. If I launch the app first, and then plug in the DGX, it asks me if I want to use their custom drivers or the system drivers (For Audio I assume). MIDI works in either scenario.

n-Track is pretty cool and works very well, but I’ve been into the HALion ‘sounds’ for ages and would much like to work with those on the go. I’ve enjoyed working with Cubasis itself (no interfaces attached), but I really would like to team it up with the Digital Piano.

I do have “MIDI Connector Pro” and “MIDI Hub” apps from the Google Store and have tried these. Neither of these Apps detect the DGX MIDI ports properly either. They see two Yamaha Portable Grand MIDI ports, but neither of them ‘work’.