If you want the printer to print a confirmation report, in most models, you can turn Fax Confirmation on for Send and Receive under the Basic Fax Settings on the front panel of the printer. Are you saying you have done this yet the printer is still not printing them? This is one of the very few Enterprise Officejet printers on the market and I do not have access to it. Post your question on the HP Enterprise Business Community to gain more exposure to other owners of this printer as well as the experts that work on them.
I will do my best to assist you though. Do not forget that your printer is also very likely under warranty. Click here to find an HP technical support center near you.