iPhone with Snapin Adapter
I had similar frustration getting my iPhone to work with the snap-in adapter.
Turned out that all I had to do was restart the iPhone. Do this by pressing the Home button at the same time as the top Power button. A slider pops up to Turn-off the iPhone. Do this. Then power up the iPhone again, which will re-start it. Then it should be found ok when you place it into the snap-in adapter.
I note that I have had to do this several times now when the Playlists disappear. Must be some incompatibility between Apple and BMW, but this fixes it.
Hope this helps.