Paid Subscriptions Group update fails
 

I have vb 3.0.7 and in the process of upgrading but suddenly my paid subscriptions have quit updating my member usergroups automatically and I have to do it manually. I have looked for some indication of what might be failing without success.

I get my email notification from paypal and I have check my IPN set-up and it looks like the manual says it should. It points to .../members/subscriptions/paypal.php which is a valid file.

I haven't found any kind of log or software trail I can look at to get a hint as to what is failing.

Any ideas?