Could you try, setting the VST Audio System to the Boss as well?

Maybe contact Boss customer support:
If you have questions about operating your BOSS product, you can contact our Product Support department by phone Mon-Fri, 7:30am to 5:00pm, Pacific Standard Time.

* Guitar/Bass Products: 323-890-3743

or Steinberg support:
http://www.steinberg.net/en/support/usa.html

Hope this helps!