Printer Setup, Software & Drivers

I bought this PageWide 552dw specifically to print out addresses on 6*11 postcards.  As I print 1,000 at a time, I wanted a printer that would not jam with the thicker paper and print relatively fast, plus hold a good amount of cards on the output side.  

I reached out to HP sales ahead of time to make sure the printer could handle the heavierweight paper.  Through my correspondence, I was convinced this printer would make the job faster.  

I spent 2+ hours with HP Support yesterday trying to get the printer to stop giving me an error of "use tray 1, paper in tray is not 8.5*11".  Today, I am going to get some #10 envelopes to try in tray 2 as it says it can use those..but guessing I'll get the same error.  

I downloaded the HP Utility and HP Smart.  Logged into the printers IP address, changed all settings to custom size paper in tray 2.  Microsoft Word shows 6*11 for the printed paper.  It will print ONE postcard beautifully, but then shows the error that the paper size is wrong.  I can't believe that a $500 printer won't allow you to set the paper to various sizes...as my little $100 Epson did!  If I send this back, I get a 15% restocking fee, which sucks since I did my research ahead of time.  

I tried downloading the latest "drivers" package, but have no idea how to get into any of that...other than changing settings in the 2 downloaded programs, the IP address, and also through the printer menu screen.  I also tried saving my file as a PDF and printing from there.

Hopefully someone has a fix for me?