The problem has been there (for me) since before Catalina. I changed a drive for a higher capacity one, and now have it slaved with an enclosure. Any time there is the slightest physical disturbance to the drive, there is a report of having unmounted the drive without ejection. Subsequently, the drive gives the error message "com.apple.DiskManagement.disenter error 49218". I keep the drive in the hope that one day, Apple will look at the problem! I am not holding my breath.