I'm running DT Register version 4.2.4 on Joomla 3.9.12. I noted after trying out a feature the other day that in this latest version, when a user registers for an event, selects a Pay Later methods and later goes back to edit their registration before the cut-off date/time, when checking out it only gives them the option to pay by Paypal, which is the second of the only payment methods I have defined in my payment profile (only Paylater and Paypal) and unless you proceed to check out via Paypal, it will not finalize the edit(s) you made to the registration. This was never is issue in the past.
Thanks