Meshes that are colliding that are set as constraint actors don't follow the Physics Constraint Actors "Disable Collision" parameter if they are colliding prior to being set as constrained actors.
Foundin 4.24.2 CL#111020242
Reproducedin 4.23.1 CL#9631420, 4.26 CL#11421855
1. Put two cubes in a scene, one above the other set to "Movable" and enable "Simulate Physics".
2. Put a physics constraint actor next to them and enable Disable Collision.
3. In the level blueprint in Begin Play add a delay node and call "Set Constrained Components" attaching both of the cubes.
4. Play or simulate the scene.
Results: The cubes still collide after "Set Constrained Components" is called.
Expected: The cubes stop colliding after "Set Constrained Components" is called.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-88923 in the post.