Re the cable discussion:

Yes, I am always suspicious of cables. I have used four cables. Two were USB cables, and I had the problem with both of them. Neither of the cables has any AWG markings that I can see. The other two were MIDI-to-USB, with an active device that translates MIDI to USB. Again, I don't see any AWG. All my cables have been relatively short.

The one I am using at the moment is the Yamaha device with the MIDI-USB converter. I bought this device specifically to see if it would fix the problem.

I also was concerned about my USB hub. It is not in the loop, but I disconnected it anyway to see if that made a difference. No change.

I don't have a computer nowadays with a MIDI-compatible connector. It would be interesting to try that.

At any rate, I will continue to look into the cable issue some more to see what I can come up with.

Ed