When running an Active Directory Discovery to collect group and members and domain controller data it seems to get stuck and hangs at "Creating Discovery Task Executor" step seen in the discovery Activity:
By defaults, Discoveries are set to use the Automatic Domain Controller Selector to select the DC used for the Discovery. First ensure that the DC being selected by the discovery is accessible to the ER server and the Nodes. If needed, choose Select available domain controllers and choose a specific DC that is known to be accessible.
If the issue was not due to the Discovery using a DC that was not accessible, reinstall the node or nodes from the cluster that is running the discovery task and try again.
