I just spoke to three different representatives at ProSeries about the signature not being printed. It is my understanding that the ERO's EFIN/PIN on the 8879 is the ERO signature. 

According to the IRS:

https://www.irs.gov/e-file-providers/self-select-pin-method-for-forms-1040-and-4868-modernized-e-fil...

"What is an ERO PIN?

The ERO PIN is the ERO's electronic signature. For consistency, each ERO is encouraged to use the same 11 numbers for their ERO PIN on all returns for this filing season. The first 6 positions of your ERO PIN must be your EFIN and it must match the EFIN in the Submission ID. You may select any 5 digits except all zeros for the next five positions. It does not take place of the taxpayer's PIN. A taxpayer PIN is also required."