Thanks @Chris White we had turned the Lazarus process off. Since we were still having issues with Zombie Killer, we were trying to move towards simply having the flow fail (without any Prefect driven retries via Lazarus process) if a task is zombie killed - and have implemented flow level retries based on that expected behavior on our end.
We'll give turning on Lazarus process another try. Although with the zombie killer issue we've seen here I feel like its a little strange that the task was marked as failed but no other tasks even attempted to run (if so, they would have all hit a TriggerFailed situation and the flow would have failed). Seems that some state other than running at the flow level would make sense if no other tasks are going to run.