Exactly the same here.
Line 6 support have been pretty much useless.
It is almost certainly to do with permissions somewhere in the installer/kext loading process which is fundamentally Apples problem for screwing up up badly. However, Line 6 should have fixed it by now. Disabling csrutil a: doesnt work b: isnt a viable option unless you want to leave your system vulnerable. Neither is using a beta OSX release because who in their right mind would do that?
I have a studio GX and a floor board which a entirely useless right now, very frustrating,