Ubuntu 18.04 seems to have a harder time auto-installing/configuring our office printer. As a result users were unable to perform certain printing tasks, like duplex printing.
It turns out that the auto-config is based on ZeroConf being turned on at the printer AND the computer ends.
In order to fix it, I turned off ZeroConf (Rendezvous/Bonjour) on the printer (which broke the iMacs printer setup) and went through the process of manually configuring the printer settings on the lab machines. I then bundled it in to the hcmc-conf package and rolled it out to the lab.
For reference, here's how I manually configured the printer:
1) Get the right PPD for the printer. I've stored a copy of the current one here
2) In the gnome control centre go to the Printers section and click the "Additional Printer Settings..." button
3) Click the "Add" button
4) Select "Enter URI" from the menu on the left and enter "ipp://printer.hcmc.uvic.ca:631/ipp" in the "Enter device URI" field. Click "Forward"
5) The system will look for drivers and present you with some choices.
6) Select "Provide PPD file" and browse for the PPD file you downloaded in step 1. Click "Forward".
7) Continue through the setup to customize your default print settings.