Onkyo receiver / Pioneer VSX receiver volume issue

I installed the app Onkyo receiver / Pioneer VSX receiver yesterday and i am having an issue with the volume control.

When i use the app and try too the change the volume the volume does not above about 50%.
I can press volume up button or slider in the app what i want but around 50% it suddenly stops and then nothing happens. (with the original remote it goes up to 100%), volume down is no problem, but up again it stops at about 50% (= ca 42db)
The volume slider in the app is fully white (at 100%) but the receiver itself is only at 50%, so something is going wrong, don’t know what exactly.

I am using a Pioneer VSX-922 receiver and running latest official Homey firmware

Try a search, i believe there are already some topics about this problem.