The solution that worked for me was to use :
trace_mode=1
This is capturing both version of the message, I think this is about using a core event hook instead of a transaction callback
3.18. trace_mode (integer)
If set to 1, the module uses core events triggered when receiving or sending SIP traffic to mirror traffic to a SIP capture server using HEP. It will automatically do the mirroring of all traffic, no need to set the siptrace flag per request.
If set to 0, no automatic mirroring of SIP traffic via HEP.
Default value is 0.
Example 1.18. Set trace_mode parameter
...
modparam("siptrace", "trace_mode", 1)
...