@vimproved this is simple, they do not support the kind of packaging you are attempting to do.
packaging juce is a bad idea, their API breaks quite frequently and so you would need to package juce separately for every minor release.
vital[ium] is an example of a plugin where it renders correctly in juce6.0, but gets very messed up in juce6.1. and that version of juce is not maintained anymore, they are already moving on with juce 7.x and soon juce 8.
@falktx
Yep, it's just unfortunate since so many otherwise very high quality plugins use it