Trouble with PagerDuty Legacy Integration

I am having a hard time getting the Pagerduty “legacy” integration to work on my on-prem sentry installation.

Plugin Version: 9.1.2
Sentry Version: 9.1.2

When I click “Test Plugin” I get a “No errors returned” message, but not Alerts have been sent to the Pagerduty service whose key I am using.

I’ve tried pointing to “Events API V1”, “Events API V2”, and “Sentry” pagerduty integrations, but nothing seems to result in an alert being created in Pagerduty.

Is this legacy integration no longer functional?