Exactly the same issue here 
I had a pretty dirty achitecture for a pure blueprints-made VR project with a simple character owning 2 hands meshes, 2 hands sphere colliders, every function doubled (right and left), etc. and as soon as I switched to a cleaner architecture with just 2 child actors refering to a dedicated “hand” blueprint, everything collapsed !
The project cannot package anymore (same error than below), and if I close it, the project crashes at start unless I remove my character class from the Content folder…