I can't see my Canon MG5220 printer... Initially I was getting "there is a communication error" so I rebooted everything, reset the printing system, reinstalled the driver and still NO luck! It seems to see the scanner, but never the printer. HELP!

The printer component uses a different protocol to advertise itself on the network compared to the scanner component and it can take several seconds longer to appear after the scanner has.

That said, with the introduction of AirPrint, the MG should be seen as Bonjour Multifunction in the Add Printer window, as shown below.

Selecting this Bonjour Multifunction entry will create a printer using AirPrint and a scanner using the iCA driver.

So do you see the MG5220 as Bonjour Multifunction or just Bonjour?

The communication error with the scanner could be a result of not having the MG5200 scanner driver installed. There is an alternate driver, known as ICA, that would have been downloaded from Apple when you add the device previously. To see if this is still working, open Image Capture and select the MG under the Shared section in the sidebar (assuming it will still be shown) and see if this will let you scan a document.

As for the printer not appearing in the Add Printer browser, I suggest you try enabling the LPR protocol setting to see if this helps. The setting can be found via the following menus on the printer.

Settings > Device Settings > LAN settings > Other settings > LPR protocol setting > Enable

Do you have the built-in firewall enabled or any installed application, like Little Snitch, that could block the canonijnetwork protocol?

If you open Finder and select Go > Go to Folder and then type (or copy/paste) the following line

/Library/Printers/PPDs/Contents/Resources

and then press GO, do you see a CanonIJMG5200series.ppd.gz file? If not, then please install this driver and then see if you can add the printer.