By design. Log warnings added to make this more clear.
Physics Constraint no longer constrains conponents that are set to Query Only
Regression from 4.11.2
Testing a 4.12 copy of my 4.11 project and when I tested in editor, all my physicscontraint blueprint objects all had their doors fall to the ground. Seems that there was a change in PhysicsConstraint in 4.12. I would have it just reference the door and doorframe before in previous builds as shown in the attached screenshot. But whatever is different now, doesn't constrain with my converted copy. But for all I know this isn't a bug, but rather the new way of using PhysicsConstraints in 4.12 and I just don't know what is wrong.
1. Open the attached project or follow the 'from scratch' steps
Results: The physics constraint will be broken and the box will fall to the ground
Expected: For the object to be constrained even with one constrained object set to Query Only
1. Create an actor class BP > open it
2. Add 2 Static Mesh components
3. Added a Static Mesh to both
4. In the Viewport, place one above the other
5. Add a Physics Constraint component
6. Set the Component Name 1 & 2 to the 2 Static Mesh component names
7. Go to the StaticMesh component > Collision > Collision Presets > Set it to Custom
8. Set the Collision Enabled to Query Only
9. Go to StaticMesh1 > Simulate Physics
10. Compile & save
11. Place actor in level & PIE
Head over to the existing Questions & Answers thread and let us know what's up.