After a more detailed check if looks like the issue happens only if the account has multiple enabled push services (ie. for more than one client) and at least one of the filters for one of the rules will decide to not generate notifications, it will stop notifications for all other services.

Example: We have 2 push services enabled. Service A has push notifications for MUC room test1 set to when mentioned while service B has push notifications for the same MUC room test1 set to always. In this case if the body of a message from the room (notification) do not have a user nickname then notification will not be generated to none of the push services, whiel it should be sent to the service B as it has rule set to always.

I've verified on a new build of the server that changes made in this task resolved the issue.

@wojtek Should we update our clusters with this new version containing this fix?

IMHO we could, even though the issue is rather niche (I'd argue most users have single mobile device)

Yes, but even old entry from old device my impact notifications on a new device. I do not consider this right now to be a big issue, so I suppose we can delay that and publish fix later on, ie. with 8.5.0 release.

+1 for slating it for the next update without making it priority right now.