We are using a Notification rule, with the Recipients defined by data page results. The data page simply runs pyGetPartyIdentifiers report definition (on Index-WorkPartyUri class), so the only parameters sent are the current work object pzInsKey, and the value "CaseOwner" for party role.
The notifications are to appear on the screen, via the notification bell, rather than through email
We have found that for notifications which have been sent to multiple recipients, the Data-Notification-Recipient instance has existed for longer than the case in question, which suggests that unique ID generation has gone wrong.
Pega-Notification instance N-001 has a CommitDateTime of May 1st,
There are 2 Data-Notifcation-Recipient instances that have a NotificationID of N-001:
One has the correct recipient ID, and a CommitDateTime of May 1st, while the other has a recipient ID that shouldn't be notified, and has a CommitDateTime that is before the case in question was even created