Just a heads up that including meshes modified with the new Mesh editor can cause packaging to fail without much info to go on:
UATHelper: Packaging (Windows (64-bit)): LogWindows: Error: Fatal error: [File:D:\Build\++UE4+Release-4.20+Compile\Sync\Engine\Source\Runtime\RenderCore\Private\RenderResource.cpp] [Line: 128]
UATHelper: Packaging (Windows (64-bit)): LogWindows: Error: A FRenderResource was deleted without being released first!
Guess there is a reason it is hidden. 
Searching that brings up https://answers.unrealengine.com/que…ng-releas.html
The mesh in question is vertex painted so maybe it’s relevant?