I don't know if it's the dealer, they have no issue ordering them for me but when the request goes to BMW over in Germany they are saying it is illegal to send that item here. Usually only happens with Euro only stuff, but I may go there today and see what the heck is going on. It is a US part, so it getting denied is not logical.
There are some random parts on US cars that end up being blocked for no reason and it's frustrating as hell. We spoke with a BMW rep at SEMA in 2016 in hopes to get more info and finding a workaround for their policy and all we got was a blank look. BMW seems totally oblivious to why this is even a concern among enthusiasts.
If you need blocked Euro parts let me know. We work with a dealer in Europe specifically for this reason. Shipping takes a bit longer and is a little more expensive, but it is an option.