For us, after the PayPal payment arrives, the record is getting generated but DT Reg is no longer sending out admin and user confirmation emails. This seemed to happen around the same time our regular registration deadline passed and DT Register had to start adding the late fees.
I can manually go in and send them to the individual, but to send them to the admin is a royal pain in the rear. There needs to be a way to re-send the admin email also for this reason and for the reason of updating a person's record.
I installed 3.1.11c and it seems to have fixed this e-mail problem. We have only had two registrations since, but I have received the admin email for both of those.