Cannot write to HID USB device (Arduino, V-USB, HidSharp)
Found the error.
While the HidSharp was sending output reports, the device driver expected feature reports.
Changing the line

0xb2, 0x02, 0x01,              //   FEATURE (Data,Var,Abs,Buf)


to

0x92, 0x02, 0x01,              //   OUTPUT (Data,Var,Abs,Buf)


resolved the issue.