Jira Webhook Subflow failing after execution

Hey there, team.

I've been working on this Jira / SNow bidirectional integration for a bit, and we've reached a snag that I can't seem to unravel. 

We can create and update fields in SNow and have them send to Jira. But when we make a Jira update, the webhook triggers the subflow, but we immediately error out with a security error at "Look up problem record." 

When I look at the execution log, it says the subflow is being run by "guest." So, I changed the Run As configuration to be System Administrator, and tested again, but it's still running as Guest.

In order to try and correct this, I even temporarily granted our "guest" account Admin privileges, but that didn't override the security constraints.

What am I missing?