[hardy]

First success: 
I played a gig with several sets.  The tablet was switched off between them. 
OTG adapter and a USB cable. The connection was stable. Every PC and CC was recognized 
But this time no bluetooth at all. 

[off topic]
Sometimes I activate the tuner to mute the Stomp. Avoid noise while changing instruments.
Choosing a new song (sending MIDI PC) deactivates the tuner and returnes to play mode.
Nice feature.