Some powders will fluidize better than others. Depends on what company makes it along with the powder itself. White seems to be a problematic color as it is heavier then most colors. Fluid bed media plays another important role along with the fact if there is any moisture in the powder. I have 6 fluid cups with several different medias for 6 of the most common colors I use. Picking the right media is done by trial and error. I try not to use CSI powders because they all don't fluidize, so I have a company that I buy my powder from. The only thing is you have to buy 50 lbs at a time, which is more than most people would use in a lifetime.
As far as using a air compressor, I don't think that will solve your problem. What I believe will happen, is that you will just have bigger volcanoes and more of a mess. You can try it and see what happens, then let us know. You can also try a small vibrator attached to the cup or under the cup to move the powder around along with the air pump. I am certain that you need to look at different media for your other colors which may help solve your problem. JMO.