Paid subscription problems
 

I've been having trouble with some of our paid subscriptions - most auto renew just fine but some don't and I can't find a pattern with any of the ones that don't. The payments are being made in Paypal, but vB simply isn't logging it so it's not receiving the communication from Paypal. I went through and made sure the API settings were correct and changed the IPN URL in Paypal from my domain to example.com, as has been suggested by others and in the documentation. I've read over and over that the IPN URL is not required by vB, yet you cannot delete the URL field, as Paypal requires something to be there. So I entered the following URL, character for character without changing it to match my domain:
http://www.example.com/forums/paymen...?method=paypal

I'm also finding that on the paid subscription ordering page there is no "Buy Now" button to finish making the payment. It's simply gone. I reverted all of the templates just in case to see if that brought back the purchasing button but it hasn't. I also figured that it might have had something to do with changing the Paypal IPN URL so I changed it back and it had no effect. I'm sort of stuck here. Does anyone have any idea what would make the order button disappear on the ordering page (/forums/payments.php?do=order)? It would seem that it's a problem with Paypal communication. What steps can I take to test and troubleshoot all aspects of the communication between Paypal and vB besides the Test Communication link? I just tried that test and am not getting the Passed result like I did before I changed that IPN URL - I tried changing the URL back to what it was before and it still didn't past the test. What other special situations should I check for? Any list of add-ons that might conflict with paid subscriptions? I have a bunch of add-ons and can't really afford to turn them all off and reset vb to stock to try and track down the problem.