I downloaded the subscription add-on from your site yesterday. There are no updates to the plug-in or add-on available.
The plan was created in LIVE mode and shows Live Mode under “Mode” on the RHS of the page.
I tried uninstalling and reinstalling the Stripe plug-in and Subscription add-on. All of the values were retained, so this looks like some kind of registry problem to me. I am using the latest version of WordPress 4.9.8