I'm not clear what you are actually trying to achieve because of...
using the adjustment layer to add particle effects
...which actually sounds like complete nonsense and a very newbie approach. Adjustment layers act like "filters" for the layers below, so I don't see how using thme to generate a bunch of particles would make any sense. Hence everything is probably working as it is supposed to do - putting it on top of the stack will eradicate the layer content below because of the inner workings of adjustment layers. Simply turn off the adjustment layer switch and let the particles render directly. If there are other things going on, pre-composing may be necessary.
Adjustment layers effect everything underneath them. Your particle effect is compositing through your entire layer stack. There are ways to work around this: changing the effects blending mode to add or doing what Mylenium said, but those are just work arounds.
You shouldn't have to use a work around for something that "should be no big deal". Anyway, the correct thing to do is apply the particle effect to a solid like everyone else. Don't add effects to adjustment layers. Don't use adjustment layers until you need to. How will you know when you need to? You'll know when you need to use an adjustment when you're back here asking why you can't get a simple thing to work & somebody tells you to use an adjustment layer. Until then, don't use them.
BTW...That belief that you know what "should or should not be a big deal" may have something to do with your confusion about how to achieve what you're trying to achieve. Whatever that may be.
There are a bunch of effects that completely take over a layer and none of these will work on adjustment layer. Effects>Simulation>Just about anything in this category will take over and obliterate all layers below. The easiest way to keep out of trouble is to remember that an Adjustment Layers is for adjustments, not effects.