external tone generator (Yamaha Motif rack) connected by USB to an iMac shows up in MIDI Studio but not in Logic

I would have expected the Yamaha Motif rack tone generator to show up in the channel strip instrument list, as does one other external instrument I have hooked up to Logic, but it does not. I installed the only driver for the Motif rack tone generator that is available for macOS 10.15.7. Yamaha said it is a routing problem with Apple and/or Logic.