This is a bug in Audition where they are incorrectly incrementing the ref-count of the IPlugView* that is returned from IEditController::createView(). When the object is released it doesn’t get deleted because it still has a reference count of 1 and, whilst this was masked in previous JUCE versions, this commit means that we no longer create multiple editors hence the blank GUI.
We’ve added a workaround for Audition to develop here so the old behaviour will apply:
I’ve submitted a bug report to Adobe (Bug: Audition incorrectly increments IPlugView* ref-count after calling IEditController::createView() – Adobe video & audio apps) so hopefully this will get fixed in Audition at some point and we can remove the workaround.