Strange behaviour when using self_collide=False

[AndrePatri]

Hi everybody,
I am using the URDF importer to load a complex quadruped robot in Isaac Sim. When the self_collide tag is set to False, the robot operates as expected. When I set it to True for generating more realistic data, the joints at the hip seem to reverse order. I'm thinking that maybe is an issue related to the fact that the visual meshes are also used for collision. My URDF has separate tags for visual and collision, and I am pretty sure the collision don't self collide. Does the URDF importer use separate visual and collision meshes, if available in the URDF? How can I check it?
Thanks in advance