I'm having the exact same problem and I can't find any solution. The updated driver instructions specify we should manually uninstall the current driver but provides no instructions as to how to do so.
I stumbled upon this page:
http://line6.com/support/page/kb/_/recording/computer-audio-set-up-and-troubleshooting/how-to-uninstall-line-6-drivers-from-mac-osx-r85
But it's the same problem.
Were you able to find any solution?