SNMP DCA suddenly stopped working

Hi; in our configuration we have SNMP DC monitor is applied on specific nodes, it was working fine and i was able to monitor the weights, but suddenly it stopped working may be after aupgrade to v13.1.1. as i cann't see any SNMP traps from F5, and there's any new input in snmpdc.log when i enable the logging. what would cuase SNMP DCA monitor to stuck, and how to solve it?