GM along with most automakers don't have an elaborate system set up for detailed tracking of every part and available option in their catologue for the general public, or even the dealers. Since most of their business is just orders from dealers for stock, and not a lot of individual orders, they really have had little incentive to develop a better tracking system either. So patience is the key.
With limite options, like chrome rims or automatics, it is not unusual to have restrictions on the quantity available to order and build. It is dependent in large part on what the supply can give.
I guess if you ordered any options that have some restrictions, you just need to stay patient while supply catches up with demand. :cheers: