List-to-Hierarchy Subscription Fails to Launch, Am I Being Obtuse?

Summary: I've got a new list-to-hierarchy subscription that's failing to launch. No error in the subscription, just never launches. At this point, even a failed subscription would be a win…

Content:
Here's the goal: A list-to-hierarchy subscription that accepts Nodes from source, adds them to the target hierarchy, and then manages moves whenever the -Source Property for Target Parent updates. Simple, right? Should be fully functional in 26.07.
Here's the setup:

• Source is a list viewpoint where I import a flat dimension from an ERP (not Oracle)
• The flat dimension member names actually represent a hierarchy (format: Level_1.Level_2.Level_3… etc.)