OK. I see what’s going on. The gateway was really only intended to update based on the results of the IPN… originally anyway. I’ve set it to update the transaction ID upon return. The IPN is still what tells CT1 to mark an order as the completed status, because PDT and auto-return can’t really be trusted, but at least you’ll have the transaction ID saved in the meantime.
CT2 has a few more features where Paypal is concerned…. to allow you to control the Paypal transaction flow a bit more. But CartThrob1 doesn’t really consider anything other than a successful IPN notification to be the conclusive “completion” of a transaction.
I’ve marked this closed now because the issue is fixed for you. Future versions of CT1 will also have the same feature built in.