I have exactly the same problem: When opening the standalone Piano V3 (connected to Keylab 88 mk 2), then loud notes simply won't play - they get muted. When I hit the keys softer, everything is normal.
Interestingly, this didn't happen when I started Piano V3 for the first time: it first did its automatic velocity curve calibration and then let me play as loud as I wanted - without any problems.
The next day, when I loaded/started Piano V3, this problem occurs, and ever since...
I definitely have the most recent software version since I downlaoaded and installed everything last weekend (=3 days ago).
THis bug is extremely annoying as it doesn't let me properly play this instrument at all.
Any kind of help would be terrific!