Following the yesterday's Nimbus version upgrade from v.20.4 CU5 to v.20.4 CU8, we faced an issue.
Under the OC's Setup Wizard tab the Primary Hub's Discovery Agent is not available.
In random timeslots, it is available for a very short time.
As an alternative, we utilize the secondary Hubs for any discovery actions.
In addition, I am not sure if recently (before the version upgrade) we had the same issues. Nevertheless, in the past, we could utilize the specific Discovery Agent.
On the Primary hub:
If that doesn't work try the following: