I wanted to know what was changed in SONAR to cause the issue, not what was wrong with my plugins. We eventually found that out though.
X3D caused a different behavior in the product compared to X3C and an end users expectation. X3D DID cause the issue exposure. We know why now. If something works in X3C and does not behave the same in X3D, then there is a perception things are not working and X3D caused the issue.
From the release notes on VST3 - Improved VST3 Plug-in Preset Support
improved vs. more fully VST3 spec implemented, as Noel eluded to, is not the same to the end user who casually reads this release note.
I have faith that this will be resolved by Cakewalk and the plugin developers.