If you set up your camera to shoot black and white, you will get a black and white JPEG, but a color RAW. RAWs are always in color (not counting monochrome cameras like some Leicas). What you are seeing in Aperture, Photos, and RAW Power is the embedded JPEG, which is also rendered in black and white. Aperture will replace that embedded JPEG with a color one (depending on how you have set up the preferences). Photos will also replace the embedded with its own rendering, though it may not do it right away (What to do about embedded JPEGs is a constantly evolving / changing thing.).
I just imported a Sony RAW that was set up that way and Photos first showed it as black and white and then replaced it with the color version. I’m not sure what you are seeing, but that behavior is what I would expect.
RAW Power does have a setting to control some of that behavior, but it doesn’t apply if you are using Photos because Photos is already replacing the embedded JPEG.