Printer will only print documents in monochrome (colour selected) yet prints colour diagnostic pages

[ChrisG20]

I know my printer can print in colour as the Print Quality Diagnostic Page prints in colour fine. Ink levels are fine. I think it is a driver/ software issue. When I print from Word (MS Office) or from a PDF (my PC it opens PDF's with Edge) or from a Webpage, it always prints in monochrome no matter if I select colour from the Print Options menu or not.   I have just tried printing a .JPEG; I see that a message has come up in the options saying 'Colour mode was changed from Colour because of a conflict with another printer setting.' I wish I knew what that printer setting is as I have not been able to find it, and it keeps over-riding everything. I think I have tried everything I can think of, clicked on every menu option- explored every drop down, checked the settings on printer itself as well. A printer driver check says that it is up-to-date. I am running a Windows 11 computer,  with a HP Deskjet 4650. Things used to work fine until several months ago (don't ask what happened then, I have no idea). Any advice?

[Repairatrooper]

It could be as simple as the wrong paper type. The drivers are programmed to reject or modify print jobs that do not meet the abilities of the printer. Often having the paper type set on the printer as any type will stop most print jobs as the printer does not know how much ink the media can tolerate.