Here is a situation when this may happen let’s say you push a Indexer Cluster bundle from Cluster Master.
When the bundle is pushed from the Cluster Master, it compiled the list of peers that are up and where the bundle has to be pushed.
After that Cluster master wait g for all peers to return the status after applying the bundle, if it does not happen the Cluster master will not get out of the Maintenance mode.
To confirm if this is your situation run (splunk show cluster-bundle-status) and check which of the client is not on the latest bundle and fix the issue with ot , and restart
