It’s the same symptom. If the BG colour is black, then the bitmap I render to the DC is black. If it is a lighter colour then the bitmap in the DC is exactly what I see on the rendered view.
This sounds like some strange blend function is on. Perhaps you are modulating source color by destination color or destination color by source color. try glDisable(GL_BLEND) prior to drawing the bitmap.
If this works you need to fix your overall OpenGL state management.