I’ve mailed the KB3D people about this sort of thing. It also happens with the previews in the content browser not showing correctly. I think maybe they have some sort of automated way of making the project that doesn’t actually involve making a real project. If you get my drift.
Anyway, the only way I’ve found to fix it, is to right click on the meshes in the content browser and
Often it only works for that session, but you might get lucky.
PS: meshes, not blueprints…