Not an expert here at all but just to make a comment based on experience. I don't know why this happens but I know it does. May start the day with a blue/white combo jig or red /white combo jig and the fish just can't leave it alone. Hit almost every cast. Then all of a sudden the bite just stops. Change colors to say a char/white, red/char, solid white or solid char and the bite picks right back up. I have always thought this has a lot to do with the angle of the sun and light penetration into the water. The lakes I fished in Arkansas was always a stained color and never real clear. It just seems the light penetration is the key and of course that has a lot to do with cloud cover, sun angle, and water color. Combo colors seem to work in almost all conditions but crappie do change their preference throughout the morning or afternoon. Just my experience.