I don't have the snap-in adapter, but the same thing happens to me using both USB or Bluetooth. I found the problem to be inconsistent signal quality on the data side, which then causes the system to default back to iPod.

On a side-note, I just heard from BMW Germany that around October, the BMW apps/smartphone integration modules should be available for local dealer install! If I hear more on that topic, I'll post it. For now, I don't know which models will have it available to them, but I would imagine post LCI at least.