RigidBody.velocity incidence on NavMeshAgent movement capacity

Hello,

I have a NPC with a rigidbody. This NPC is controled by a script which make it move randomly in the world, detecting collisions, stopping, controling its environnement and turning to go elsewhere.

When the Player enter the "chase collider sphere", i activate the NavMeshAgent to chase (then destroy) the Player.

But to do my random patrol duty, i use rigidbody.velocity = transform.forward and to stop this patrol i use rigidbody.velocity = Vector3(0, 0, 0);

The script works if my NavMeshAgent is activated at the creation and chase the player. But once i stop the NPC or do my patrol duty (with transform.forward or 0,0,0), the navMeshAgent is totally unable to move the NPC.

Anyone encountered already this problem or have a clue ?

Thanks for your answer.

Best regards,