I’m using Casio AP-25 which is very old model but it supports MIDI.
But when I tried to connect to my pc and run some vst. I had a same issue.
You can refer the youtube video that I reproduces this problem.
This happens not only in cubase but also in other applicaton such as musescore.
I think I need to make final conculsion that this is problem from my digital piano.
If anyone has better idea for this issue, please reply to my post.
Thanks