So to confirm:
Dev Console -> Extensions -> Manage Extension -> Manage a Version -> Monetization
You have this option enabled:
Dashboard -> Extensions -> My Extensions -> Manage Permissions
You have the second toggle enable? (It’s disabled in my screenshot)
Finally you are testing on the Twitch front end (the actual website) as a user whom has a subscription? The above quote suggests you are testing it in the Rig and the behaviour may vary. Certain parts of the Rig don’t work as expected in the rig.
You can and should add a test:
To check if sub status is actually available, documented at https://dev.twitch.tv/docs/extensions/reference#helper-feature-flags
Before running the code you used which doesn’t do the “enablement” check.
I predict the issue is, that you are testing in the Developer Rig where subscriber status just isn’t available/not working as expected, or could be a bug. And the checkbox you refer to:
Just turns on the feature flag doesn’t set the “user” as having a sub
The feature flag being:
window.Twitch.ext.features.isSubscriptionStatusAvailable as mentioned earlier.
For best results install the extension to a “real” Twitch Channel and test there.