I got everything working on Catalina after getting a new Roland UM-One-MK2 midi cable. I had an old UM-One that Roland will probably never update, and they came out with a new 10.15 driver for the MK2 a couple of days ago. All the Steinberg programs and plugins were working since I upgraded to Catalina (Cubase 10, Halion Sonic, The Grand 3, Diversion) on a Mac Pro using a UR 28M interface, after some config changes and driver reinstalls.