UR22 MK2 on LG8.3 Pad - USB Audiorecorder Pro

I installed the „USB Audiorecorder Pro“ on my LG8.3 Pad and connectet it by an OTG cable to my Steinberg UR22 MK2. The UR22 is externally powered by a separate PC resp. a 7 Ah powerbank.

According to the app providers compatibility list this constellation should work.

Unfortunatelly the app crashes shortly after it has been started. It seemed in most cases this happens after a very (very !) slight touch at the OTG or the USB cable.

Obviously this looks like a bad USB hardware like worn out cables and / or connectors but I changed every hardware (exept the UR22 MK2 which is quite new and works fine on a PC) with no success.

I set up a cheap (5 Euro) USB Audio stick in place of the UR22 an this works flawlessly with the app.
However the support of the app insisted on bad cables or powersupply as reasons for the problem.

Has somebody a hint to solve or isolate the problem?