Is CBSubs publicly accessible? --- Yes, it's the "Apply Now" menu item at the top.
Ensure the Subscription tab within CB > Tab Management is published and public. --- Yes, subscription tab is published and public.
Ensure CB Paid Subscriptions within CB > Plugin Management is published and public. --- Yes, CB Paid Subscriptions plugin is published and public.
Ensure your PayPal gateway is public accessible. --- I'm not sure what you mean. If you're asking if the PayPal gateway is published, yes it is. All of the parameters including identity token and account email are correct, and we're currently receiving payments, it's just that nothing else works in relation to the transaction. No group assignment, no email to user or admin, etc.
Check within CBSubs > Notifications to ensure your PDT or IPN notification from PayPal was received properly to mark the basket as paid. --- The notifications area of CBSubs is populated with numerous items PayPal IPN notifications, including both completed payments and refunds. However, the status in the Baskets is "Not Initiated" and for each there is an option to pay, even though the proposed payment has already occured.
I wasn't able to decipher anything by looking through the error log, although there could be something that I don't know how to recognize.
Does any of this help?
Thanks,
Jordan