In Strategy 2019, connecting to an Intelligence server from Strategy Office causes the following error to appear:
MSIXML: Server ‘Server_Name’ not connected

projectsources.xmlfile to point to the same project source of both Intelligence server cluster nodes.
This is an identified defect in the 2019 Strategy Office add-in.
To avoid the error, change the
projectsources.xmlfile to point to the primary Intelligence server node. The clustering functionality should work automatically between the named node and any other node in the cluster.