Yes, I've discovered that pretty quickly. Of my various acrylic paints, some of them are fairly thick and opaque (my white, grey, brown, black, and an oddball selection of certain fairly solid "cool" colors), while others are relatively translucent and watery (any of my "bright" colors -- yellow, red, orange, vibrant purple, certain of my blues, certain of my greens).
Even without dealing with Bones, if I were painting a figure in any of those more "watery" colors, if the area I wanted to paint were dark (or if there were bits of "splash" from painting other areas), I'd need to lay down some solid white first, or else the end result just wouldn't look right (more paint would tend to pool in lower areas, leaving high areas thin, and if the high areas are dark or spattered, that's going to show through). I'm running into a similar dynamic here: If I want to use one of my "bright," more translucent colors, then I need to lay down some solid white first -- or one of the lighter of my more opaque paints. (I have a light blue that's fairly opaque that I often use as a base before applying one of my more watery blues, for a pretty nice effect.)
Unless I have something put down first to "anchor" my paint to, "washes" don't play nice with bare Bones.
A quick coating of Army painter Anti-shine (the dropper bottle kind) worked really well on my translucent "fire" minis. I just gave the full mini a coat of it, and then I was able to use washes normally.