UltraMixer 6 does not yet support macOS 11 (Big Sur). Currently we recommend that you should not upgrade to macOS 11. The current macOS update has not yet been completely tested with UltraMixer 6 in all versions.
We are working to ensure that UltraMixer 6 is fully compatible with the new macOS update.
In the meantime, we recommend you stay with the latest macOS version until further notice.