In Windows 10, I just reconnected my minidisc MZ-RH1 player to SonicStage 4.3 using the driver file NETMD760.inf that I found on this forum. The computer now recognizes both normal MDs and Hi-MDs again.
I had thought it was SonicStage that wasn't working, but it was actually the driver for the MZ-RH1 under Windows 10 that wasn't functioning. This driver is currently working (probably until the next Windows 10 update :-( .... )