Printing Errors or Lights & Stuck Print Jobs

At home with only a wired Windows 10 PC and the HP Offciejet 3831 wireless printer.

My tricolor 302XL cartridge ran out of ink so I replaced it. Sadly don't remember if it ever printed colour before I noticed something blakc and white that I had intended to print in colour. 

Printing a photo from my mobile works fine - colourful. Also tried sending a file I called:

sz180303PrinterTarget.pdf

to the printer's email address - works fine too.

Problem:everything printed 'normally' from the PC inc via Photoshop and directly from Chrome comes out in black and white only.  No colour.

So printing 

sz180303PrinterTarget.pdf

 from Windows 10, Chrome launches it's printing dialog and I see the doc in colour, but the printer prints B&W, even though 'colour' is selected in the print dialog drop-down. 

Here is a link to the actual PDF I used: sz180303PrinterTarget.pdf

Switched off the printer and uninstalled the HP software and drivers.

W10 Device Manager showed no trace after the uninstall.

Waited ten mins then switched the printer and PC back on again, re-downloaded the full HP Suite for the 3830 series.  Installed everything and ran the HP Print and Scan Doctor.

No difference, still black and white only.

Uninstalled everything again, switched off the printer and PC again,  rebooted, re-installed everything - no difference. 

Connected to the wifi my mobile prints the hp.com webpage correctly in colour, the PC prints the same hp.com website screen in black and white.

When selected at the printer or via the Windows HP Software or HPConnected.com website, the printer demo page is in full colour. The print quality report shows the printer colour cartridge is nearly full and that both are 'genuine'.

The Windows 10 Printer Test page prints in Black and White.

I have tried pausing the print queue to examine what is sent to it - there I can see, just below 'Layout' that the pdf is intended to print in colour. Prints in B&W though.

I then reprinted it, choose 'black and white' from the Chrome PDF print dialog - sure enough, the job sent to the print queue has the 'Black and White' radio button preselected. Prints in B&W.

So it really looks as if the printer firmware (at the latest level) is differentiating between jobs sent from my phone or via HP's email Cloud Print facility - they all print fine.  Jobs sent from the Windows print queue only print in B&W. Does HP have something against the W10 print spooler?

Help!