Just a minor bump - I’m still getting this in 4.17 and above.
I think I’ve traced the issue back to the Alt-Drag functionality in the level editor. When creating duplicates of objects that already exist in the world, the duplicates seem to be prone to this issue. Dragging each instance in directly from the content browser seems to fix the problem for those instances.
's an example in my case. I have two actors in the scene which reference each other. If I make a change to the master blueprint, the reference to the other actor remains for the original instance, but the second actor forgets it’s reference / set’s it to none. Anytime I change the Blueprint, I have to remember to set the instances back up. Note: The actors blueprints inherit from C++ classes, and the reference that’s being dropped is a UPROPERTY.
I’ll make a screen-cap video and update thread if I can.