Go to Data Sources-> NFA. On the Monitored Interfaces->Manage Monitoring section that's displayed the Devices list defaults to 10 items per page.
When using the Devices panes search field, it only filters using the items in the current item list.
If you have 244 devices and the pane is set to 10 per page, the filter only looks at those 10.
Set it to 500 per page to list all Devices and search now works.
It was also observed that when setting it to show non-default per page value, it would revert back when navigating to the same page again. It did not maintain the setting.
Performance Management r20.2.2
Defect in the code preventing filtering against full results set. Instead it filters on the result set on the page at the time defined by the per page setting for the Devices pane list.
This is a defect that is being resolved via defect ID DE478423. At this time there is no ETA for a release this will be fixed in. This article will be updated when one is available.
To work around the issue, set the Per Page to the max value, 500, and filter against the full result set.