Let me rephrase my question: How does the Meraki Cloud populate the list for hubs in the Site-to-Site VPN configuration for spokes? In my opinion it makes a difference if a hub network is bound to a template or if it's not. I want to understand the reason why it is that way. I did not find any documentation that points this out.
I have found out that we are unable to configure a node to be a spoke off a hub if the hub is bound to a template. This has been bugged to understand the expected behavior as it is not documented within the Template nor the Auto VPN Hub deployment guides.
I will update this post once I hear back from MX development team.
I can confirm that AutoVPN hubs should not be added to templates at all. It is not possible to configure an MX as a spoke with an exit hub that is part of a template. I will also update the AutoVPN template and deployment guides ASAP.