Emails do not appear in conversations

Emails do not appear in conversations

I received several emails from the same address, and they use the same subject, but they all appear separate.

More specifically, they are emails created by a support ticketing system, and each time the ticket is updated, I get a new email that is in a separate conversation. Gmail used to group them together.

Example subject:   [Ticket ID: 619323] Some question..

My conversation view is enabled.