There is a known issue with macOS 11.4 which may cause drivers no to load; instead of reinstalling every time, try this...
Open Terminal and paste this line:
sudo kmutil load -p /Library/Extensions/DJM-900NXS2\ USBAudio.kext/
Press return and enter your user password (if you have one, otherwise just press return with a blank).
This will force the drivers to load without needing reinstallation.
We hope that the 11.5 update will resolve this as our tests are looking positive.