Publisher fails to subscribe to a node if namespace table entry is not available during initial connect/subscribe (likely regression)

[quality-leftovers]

Describe the bug

When publisher connects to an OPC UA Aggregation Server and tries to subscribe to an underlying server that has not yet connected (or is currently disconnected) publisher fails to subscribe to the nodes even after the underlying server has connected and the namespace table has been updated. It seems like the publisher never refreshes its "view" of the namespace table.

After initial failure to subscribe the publisher logs the failure to subscribe every 5 minutes

Likely related to this issue: #1306.

To Reproduce
Similar to #1306.

A namespace table is updated on OPC UA server side after the publisher has already connected.

Expected behavior
The subscription fails because the namespace is not found in the namespace table. As soon as the namespace can be found, the subscription is created.

Screenshots
n.a.

Desktop (please complete the following information):

• Publisher Version 2.9.0

Additional context
Logs

Failed to add monitored item 'Data Item 'nsu=urn:ABCDEF/http://xyz.com/MYOPCUA/;s=12345'       
System.ArgumentException: Namespace 'urn:ABCDEF/http://xyz.com/MYOPCUA/;s=12345' was not found in NamespaceTable. (Parameter 'nodeId')

[quality-leftovers]

Adding a session.FetchNamespaceTables() before the sync logic runs seems to fix the problem. Will check if the problem (or a different one) occurs with this change.