Hello dbudde!
I can't reproduce the problem here. Sibelius finds VE Pro 6 (build 6.0.15224) AU and VST here and I can open Playback Configurations that were created with VE Pro 5.
I have seen in your previous post that you are using a beta version of OS Sierra. Please understand that we can't check our products on unreleased operation systems. Do you have another OS installed as well?
We are not planning to give up support for Sibelius.
Best regards,
Andi
Vienna Symphonic Library