Hi Henning
The issue probably was that the module logs an error if there are no credentials in the message.
Thank you for confirming my observation.
It's weird that only 'PRACK' are skipped as causing an error if there are no credentials probably happens to every messages I guess, if you didn't check for the presence of credentials with has_credentials() before 'consuming' them.
I will revert back to remove_hf().
Mit freundlichen Grüssen
-Benoît Panizzon-