Thanks so much for yuor work, just only from the number of dependancy usages, I am sure you have done a great job, this plugin is so useful for creators who are specially in cua creation, and is just what I need now. Still not many people are creating cua related things, but high quality things just come from cua creation and it opens so many new possibilites.
2)currently plugin supports 1 Skinnedmesh Renderer, if your CUA contaions 2 or more SkinnedMesh Renderer, Separate prefab.
I cannot remind other reason without CUA information you tried.