Apologies if you've tried this already, but have you relaunched the vSphere client? Just asking because it sounds like a bug.
You shouldn't need to drill down to any other entities. If it's a vCenter alarm causing this, it'll be on the alarms tab under triggered alarms for the cluster itself, and if it's a configuration issue, it'll show at the top of the summary tab for the cluster itself. If you've disabled both of those, you might review the cluster events and see if anything stands out.