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I do have Maestro configured. Unfortunately, it is on R81.20 and it is connected to regular Cisco Nexus. This is why I cannot be helpful enough for your problem investigation.

However, please, take a look at this SK. It may give you a lead.
sk168181 - Communication problems with ClusterXL clusters connected to Cisco ACI

From general Maestro standpoint. Magg interfaces are excluded from distribution, and it should not be a problem until somehow management traffic is sent/received via a data interface. Usually, it happens because of some routing mistake. I am sure that it was already checked.

If you would like to look into SMO state in more details, then you can try this zdebug command:
fw ctl zdebug -T -d 'SMO,smo' -m cluster + conf

It is very lightweight and shows changes in SMO role.

"-d" puts a filter in kernel to match string "SMO" or string "smo", otherwise module cluster with flag conf returns too many data.