We're currently aware of issues with the Paypal Auto-Return service which some of our users may be using as part of the OptimizeMember websites
This issue is affecting any website using the Paypal Auto-Return feature - and is not specific or linked to OptimizePress or OptimizeMember.
We also found this forum post which also seems to point to other people having the same issue:
At this stage we can only really advise speaking to Paypal yourself to see if they can fix this on an individual basis, but we believe the issue is more widespread and we're hoping for a fix soon from the Paypal side.
As far as we are aware this issue has now been resolved on the Paypal side. We are no longer experiencing issues on our websites although we have had no formal notification from Paypal about the bug or fix, so it's most likely this was a glitch in their system which they have now resolved.