Devices not showing after adding in OpManager

Devices not showing after adding in OpManager

Dear team,

We have an OpManager 9 build 9410 installed on Windows server 2008 OS. We have started facing a problem that is some devices are added successfully but they do not show in device search or anywhere. Also tried to add them with discovery method but still same result. The issue is faced at random on different type of devices such as switches, server, etc. Please suggest a resolution. Waiting for your responses