Same problem - using Cubase 10.5 on MacPro running Catalina. Installed UR22C Yesterday - all worked perfectly. Drivers and firmware all up to date. Today, every time I started Cubase the UR22C would disappear. Found this thread - tried removing YamahaSteinbergUSBMIDI.plugin from the ~/Library/Audio/MIDI Drivers folder (moved it to the desktop and deleted it from the MIDI Drivers folder) and rebooted. Problem solved (so far, anyway). Thanks rdb5555! Also using USB for MIDI, so not a loss - but not good for someone who needs the plugin for the UR22/44C…