Available sessions missing if peered on one IX Connection of multiple IX Connection to the same IX

[mngan]

Peering Manager version

v1.5.2

Python version

3.10

Steps to Reproduce

1. Create multiple connections to an IX
2. Create a session to an AS on one of the connections
3. View available sessions for the AS

Expected Behavior

I would expect that the sessions for the AS on this IX would still show up if there is a Connection that is missing a peering session

Observed Behavior

The available sessions for the AS on this IX are not visible, so the only way to create the session is to manually create it. Or delete all sessions to that AS for this IX, then the AS will show up in the available sessions and you can create all the sessions.

This happens a lot when we have added a second connection to the IX sometime after the first, and we want to find all the peers that haven't set up sessions on the second connection.

[dunc623b]

Can confirm same behaviour on v1.7.2 and Python 3.9.2
Same scenario here, we added 2nd connections to a couple of IXes and trying to get all the sessions in sync across both.

[gmazoyer]

To fix this issue, a change to the SQL queries generated by this function is required.