[Zubersoft]

I'm sorry to hear you are suddenly running into these issues Henk. Do you happen to know what version of MobileSheets you were running before the reinstall? It would help to know if you were on the latest (v2.7.4). If you installed the same version that was working previously, this would certainly be a mystery. If there were different versions involved, we could run some tests with an older version to see if something has changed that is causing your device to no longer be recognized.  I don't really have a lot of insight into what's happening under the covers with Microsoft's MIDI library (it's currently the only library available for UWP apps, so I hope this changes in the near future), so it's hard to say why it's not detecting your keyboard. It sounds like you've really covered all the things I would have recommended trying. Do you have a MIDI HUB you could try routing the Pa4x through so that MobileSheets is instead connecting to the HUB?

Mike