UR22mkII connection issue on Mac (Big Sur)

My Mac (Big Sur - Intel Core i5, all drivers updated) recognises my UR22mkII when I connect it. However when I launch Garageband or Cubase LE, the Steinberg disappears from the list of sound devices.
Here is a video that shows Steinberg as a device, and disappears when I launch Garageband:
Are there any kind people out there who can help me??