Channel and connection

Hi Experts,
I am using single instance of UM in a clustered(two IS) env. I have 50+ channels in UM. I can not see connection(in admin view where we see status, join, snoop, connection) for any of the document. As per my understanding, under connection we see, number of triggers subscribing to the given document. However, pub sub is working fine as usual, but if IS or UM restarted we need to re sync document types.

If I created a new document and a new trigger I am able to see the connections.

Therefore, problem is this :-

  1. Why I can not see connection for a channel(created pre migration).
  2. Why I need to re sync document types, everytime server is restarted. I am suspecting, above point 1 may be the reason.

Note :-

  1. Server migrated from older version to 9.9.
  2. New Doc is created after migration.
  3. attached is the SC to understand what I am referring to.