I’m still having a hard time replicating this locally, so could you show me what you have in your browser console when loading that page? Maybe it will have something useful in it.
The network tab for “subscriptions” should look something like this:
with a response of:
Then can you also post your console tab? There may be several yellow warnings, but I’m mostly interested if there are any red errors:
I’m also curious if the admin subscription page loads? You can visit this url /admin/plugins/discourse-subscriptions/products
and then click on the subscriptions tab.