Hi, tried out the Mixbus 3 product...
The only way I could start it, is to remove the "SCOPE ASIO" device from the list of available ASIO devices on my machine, by Exporting the key to the filesystem (so I could add back again), and then Deleting the registry key for Scope ASIO, under HKLM/Software/ASIO
I have proven I can add this key back again (by right-clicking on the .reg file, and selecting "Merge").
Mixbus is not so nice when I add the Scope ASIO registry key back in - it appears to still want to query ASIO devices each time it is launched... I now get a funky screen in Mixbus 3, now that I've added Scope ASIO back into the Registry (unprintable character in a frameless dialog window), and Mixbus is back to being unusable...
So, I can use Mixbus 3 on my system, but not if Scope ASIO is available on my machine.
Luckily, I have my Motu 828 Mk3 for ASIO duties, and can route audio into Scope over ADAT... I've two PCI cards, so I could have 16 channels at 48 kHz in and out...
So, this is strictly a workaround scenario...
Tested another DAW that used Portaudio for Audio Device interfacing - that others had been complaining about... Bitwig.
Latest Bitwig (1.2.0) behaves well if you temporarily remove Scope ASIO from the list of Scope devices, start Bitwig, choose your ASIO device, and close Bitwig again. Furthermore, it appears to persist what Audio Interface is configured, in its preferences file, and (nicely!) doesn't appear to try querying available ASIO devices again once the Preferences file is set to a (non-Scope) ASIO driver (the Motu driver in my case). So, I can configure Bitwig to use my Motu interface when Scope ASIO is removed from the Registry, then add Scope ASIO back into the Registry, and use continue to use Bitwig with the Motu...
Obviously, being in and around the Registry is something you must do with responsibility. If you don't know what you're doing, don't do it. If you think you know what you're doing, then make sure you can roll back your changes before you commit any changes. Use Windows Restore Points if you wish - they work well. If you screw up your registry, and leave yourself with no fallback position, there is nothing anyone in any forum can do you help you - it's a one way street, and you are on your own.
Think you get my point...

Not because it is easy, but because it is hard...