Say that I have two blueprints, BP_A and BP_B. Both blueprints have a scene component attached to them. Call it C. There’s a property on C, called P. This bug shows up no matter what the type of P is, but we’ll say it’s a float for example’s sake.
When I go into the blueprint for BP_A and change the value of P to, say, 100, the value of P on BP_B is also 100. There is no way to edit the property on a per-blueprint basis. This does not happen every time. Some fields seem unaffected. Some fields are affected every time. Some fields, this happens sporadically.
This happens across different components, different blueprints, different properties, and different property types. It happens everywhere. It happens after I shut down the editor and recompile. It happens after I manually clear the Unreal cache. It happens after I remove and re-add the component to the actor.
I can provide a video of this behavior, or my project (although for some reason I feel that if I started a fresh project, it would magically disappear), but the repro really is that simple for me: Edit any property on any component, and watch the change propagate to other blueprints seemingly at random.
It’s unclear to me how a bug like this could ever make it to production, but what do I know?