Printer Setup, Software & Drivers

I was very embarrassed with a customer's print job when it turned out my fancy HP printer (normally quite a nice machine) refused to recognize a custom paper size. If the paper size is not listed on the printer's drop down it refuses to print, even when I tap on "print anyway." Even when I select "custom." That is, to put it more cleanly, I can't get "custom size" to work. It simply says "paper size detected is smaller than paper size selected (custom)." (Which statement doesn't even make any logical sense, you might also notice.) The paper size I was trying to get it to print on is 8" x 6.5", basic gift card blank stock (fold it in half, you have a very nice card). Not listed. The standard solutions for adding a custom paper size show options on the printer option dialog boxes that do not appear on the real dialog boxes. No custom paper size can be created. 

It used to be VERY simple. you put in the paper and print and the printer does what it does, without trying to be papa-knows-best. Now there's not even an option to tell it that *I* know best, at least not one that works. In the Olden Days this would have worked. Now, fancy, super smart printer refuses to play the game any more. 

How come the software for this printer doesn't match the published version(s) of the software? Why does it refuse to  print even when I say "print anyway?" HP used to produce very professional software. 

By the way, latest firmware is in place. Latest printer package is in place on the workstation(s). No Joy in Mudville Tonight.  (Mighty HP has struck out.) Also, as title suggests, it is an HP OfficeJet Pro 7740 wide format, and it has always performed quite well, mechanically at least. Nice machine. But it's as if the software was never finished. 

This is very embarrassing for me as  a "professional" service provider to have to say "my printer is just won't accept this paper size." Makes me look like an amateur, instead of a 45+ year veteran of my industry. 

I don't actually expect an answer from HP (that's been my experience for some years now) -- though that would be most welcome -- but does any body have any advice that might actually a lead to a fix? Please don't quote the link to the standard HP "how to add custom paper size" article, which -- as I said above -- has no relationship to the software options on my screens. And, yes, I have uninstalled and reinstalled "the latest" version of printer package, which unfortunately is all I can find (unfortunately, because the matching software from 4 years ago would have worked just fine... as in fact it did).

Thank you for your attention and your help

-- Phil