_integrate_forces() reports contact_count=0 during RigidBody2D collisions

[mjx1905-001]

I am using Godot 4.4.1 with godot-rapier-physics 0.8.12.
The same codebase is used, with the only difference being the physics engine.
When using Godot's default physics engine:
After a collision occurs between RigidBody2D and StaticBody2D,
the rigid body breaks into two pieces at the collision point (as implemented in my code).
When using the Rapier physics engine:
After a collision occurs between RigidBody2D and StaticBody2D,
the rigid body simply stops moving and does not break into two pieces.
The reason for this difference:
With Godot's default physics engine during collision,
the state.get_contact_count() in the _integrate_forces function within RopePiece_mjx_lib code returns a non-zero value.
With the Rapier physics engine during collision,
the state.get_contact_count() in the same _integrate_forces function returns 0.
​Implementation Steps:
Simply run the project using two different physics engines to observe this behavior difference.

test.zip