The bug you mentioned is referring to a beta version of v6 of NServiceBus. You mentioned that you are using v5.2.14 of NServiceBus. Are you using conventions or the marker interfaces to mark your messages? Did you make sure that the convention picks up the message you are deferring?
I would love to help you out but without more details it is practically impossible Would you be able to create a small repro solution and share it with us?