Illegal reference to private object error when packaging projects with dmx fixture assets

Development Programming & Scripting
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1

yesterday i was getting Illegal reference to private object for BP_StaticHead. I took those out and replaced them with the same asset. Now I’m getting the same error for some BP_StaticMatrix instances (even though i didnt change these at all and they packaged fine yesterday).
Is this related to the actualy Blueprints in the dmx plugin folder or something else maybe having to do with the dmx library?

here is the error:
Can’t save ‘E:/Unreal Projects/PCG56/Saved/Cooked/Windows/PG56/Content/DMX/NewDMXLibrary.uasset’: Illegal reference to private object: ‘DMXComponent /Game/Scenes/cW.cW:PersistentLevel.BP_StaticMatrix_C_1.DMX’ referenced because it is an archetype object (private object belongs to an external map).

2

I copied all the DMX plugin fixtures into my project’s content folder and replaced all the instances in my project with the new blueprints. this allowed the project to package successfully.
I’m still puzzled by the intermittent nature of this problem.
also, are we not supposed to use content from the developer plugins folder in our own packaged apps?