OnMouse event only works for a moment and then not working

I made a randomly walking NPC with NavMesh system and I wanted to interact with that NPC by mouse event. So I used OnMouseEnter events on it.

After I play the scene, OnMouse events works perfectly. However, it ceases to work after certain time (about 3 seconds) and does not respond to mouse events. Why is this happening? I’m using Unity 2019.4.19f1 version.

Below is link of my project package.
https://drive.google.com/file/d/1wdtONaAxPrGF8GIlKDkR97bttxMxB4bw/view?usp=sharing

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Hello @ahnjinmo

Looking to your image attached, OnMouseEnter and OnMouseExit are called 4 times, so they respond to the inputs… in the Console, you have “Collapse” enabled, that unify all text that are equals, so you see them only one time…

If the player don’t do what you expect, I think there are errors in other scripts.