This is a quite unexpected behavior. I have a Windows 10 app that works perfectly well when using a simple USB to MIDI adapter and also with a Roland INTEGRA-7.
However, when using my UR44 a call to SendMessage never return if the payload is a DT1 (send data) message. All channel mode messages works, and all RQ1 (request data) works fine.
It is very confusing that SendMessage can send a RQ1 message, and that the app receives a return message, but when sending a DT1 message the call never returns, and the app freezes.
Has anybody seen this behavior with UR44?