Strange intereactions between [subscriptionform] and [level-visitors]

I'm using [level-visitors] and [level-not-visitors] codes to control what gets shown on a single page, and running into problems with the interaction between this and [subscriptionform]. The page is at http://liminality.achangeiscoming.net/channel2/membership-test/

When I'm not logged in, it renders correctly.

When I sign up at the Standard level, and then go back to this page, it shows me the Subscriptions page instead.

There aren't any other plugins running and I'm using the default Wordpress theme. I've enabled support access if you need it.

Here's the page's content:

[not-level-visitors]
<h5>Members-Only Content here, and so only available to people who have signed up.</h5>
[/not-level-visitors]
[level-visitors]<h5>Preview content, visible to people who are not members</h5>
 
<h3>To see the great content, sign up here!</h3>
[subscriptionform]
[/level-visitors]

This might be related to the other question I just asked but seems like it might be different so I'm putting them in separate threads.