Issue : WANRTT monitor stopped working in OpManager.
Solution : This could be due to the changes happened in the Cisco source devices for some reason , possibly after a router reboot.
Click on IPSLA WAN tab under Network tab -> All Monitors -> mouse over to the problematic WANRTT monitor, you will be able to see the ProbeID at the left bottom corner which is the operation id for the monitor stored on Cisco source device, connect to Cisco router using telnet and run the command " show ip sla configuration", we can see the monitor information with the same operation id , verify if it has"Pending trigger" instead of "Next Scheduled Start Time" , if so update the it with the following information :
ip sla monitor schedule <operation id> start-time now life forever
Example : ip sla monitor schedule 101 start-time now life forever
(Where 101 is the operation id)
After the above change, save the configuration by "write mem" command and reload the router.
Once done, please wait for some time and check for the data collection.