Photoshop 2019 Printer only prints black & white

it sounds like a setting may have accidentally got turned on, either on your computer, in the app, or in the printer driver.  

Are you conducting your printer tests via wifi as well or is it usb or via the printer buttons? 

If you print via USB sometimes:

When you print via wifi, do you use a different printer selection then printing by USB? Sometimes when printing via usb or wifi two different printers on the system are set up even if it ends up going to the same printer.  If so, the color settings might differ between the printer selections.

If the above does not work or does not apply:

There is a button called "Print Settings..." in the top right of the PS print dialog.  You can try checking the settings in there for color/black & white before printing.