Help! Some values of "Agent Radius" immobilize my character!

My AI works with Nav Mesh Bounds Volume. As it has to walk in a house (small space), the Nav Mesh Bounds Volume must be precise. So I decided to decrease the value of Agent Radius, so that my AI can have the greatest possible freedom of movement. But when I decrease this value (by default 35 when I put the Nav Mesh Bounds Volume for the first time) to 10 for example, my AI no longer works. I have tested and my AI can walk only if the value of Agent Radius is between 31 and 39 included. I really don’t understand how I should proceed to solve this problem! Solutions would be really appreciated!