This problem can occur if the agent's cache needs to be cleaned up.
Please note that you need to ensure that the Operations Manager agent has been configured properly after clearing cache. Otherwise, the issue will reoccur.
Please refer to the Configuring Operations Manager Agent Knowledge Base article.
Cleaning up the Operations Manager agent cache resolves the issue and refreshes the agent local configuration.
Please perform the following procedure to clear the cache. Note that in different versions of Operations Manager, the “agent service” is named differently.
Current versions name this service “Microsoft Monitoring Agent”. Previous versions of Ops Mgr named it “System Center Management Service”.
1. Stop the agent service on the Veeam Collector server
2. Delete the Health Service State folder –
i. On an agent, the path is typically %ProgramFiles%\Microsoft Monitoring Agent\Agent\Health Service State
ii. On a Management Server, the path is typically %ProgramFiles%\Microsoft System Center 2012 R2\Operations Manager\Server\Health Service State
3. Start the agent service
The service will rebuild its configuration file, download MPs, initialise, and monitoring will commence.