To resolve this issue, follow below steps
- Double-clicked on “Health Service” on the affected agent. On the Actions menu, select “Health Service Tasks -> Flush Health Service and Cache”.
- Restart OpsMgr Health Service.
A few minutes later, health status in Health Explorer was reset to green.
If still have this issue, Put server in Maintenance Mode in 10 min. Then wait after 10 min, Health status will be green.