CMYK greyscale changing to RVW

First time for me to experience this strange problem. I have applied a percentage of CMYK black from the CMYK color palette to some lettering & contours, and then when I click on them later it shows (in the bottom/right corner of the screen) to be a RVW color (Roland VersaWorks).

No matter how many times I try to revert it back to CMYK, it goes back to RVW. Any ideas why and how to fix?