Computers automatically being removed after xx minutes

Hello/Bonjour

I have an issue with my OCS servers. Some computers are disappearing from inventory.

For example : one computer is missing, I make a manual inventory, I see it in the server, then, after XX minutes, it is not anymore in the server.

Is there an option that can cause this ? I cannot figure it out and it drives me crazy.

Thanks

(OCS Server 2.3.1 with EyesofNetwork (CentOS appliance) / Agent 2.3.0.0 and 2.1.1.1)