Some of the discovery schedules in our MP are long - at least one hour, sometimes several hours, or even once per day.....this is Microsoft's Best Practice rule for application discovery.
So sometimes you do have to wait several hours for at least the initial discovery for applications (such as Veeam Collector).
And the discovery of the Collector Heartbeat object actually runs in the agent on the Veeam Extensions Service Server - because this is where the heartbeat is monitored for all Collectors.
This discovery is scheduled to run once per hour. It is controlled by discovery rule "Veeam Virtualization Extensions for VMware Topology discovery".
If you want to force discovery to run, you can restart the Systems Center Management service (SCOM Health Service) on the server where Veeam Extensions Service is installed. Restarting the SCOM Health Service forces all (unsynchronized) discoveries to run.
Hope that helps - let me know how it goes!