When you create a new event on Jira instance, using the generic template, and associate with a transition on the workflow, the transition trigger doesn't fire. For example, when an issue is transitioned to "In Progress" fire this custom event set in the workflow and created an automation rule when an issue transition to "In progress" - this rule is not triggered.
Normally, custom events are created to customize the notification of specific users during the workflow. Note that it is not possible to fire two different events in the workflow transition.

Suggestion: Find a way of considering anytime that an issue is transitioned to a certain status, trigger the rule - not depend on the fire event in the workflow OR create a new trigger to fire in custom events.