-GPUs in claymore are seen in hex. So, the index goes 0-9, then a-f. Your 11 and 12st GPU should be a and b respectively.
-Claymore supports way over 12+ GPUs. But it becomes a headache for the Operating Systems. Your best shot here is adding Nvidias. Please read the entire "readme.txt" file.
-Don't use MSI AB then, just use Wattman instead, or w/e software suits better for you.

I don't know if those were real questions or a excuse to brag about your rigs haha. As mentioned by OP, you (or w/e built that for you and charged you PREMIUM COSTS, hence the ad) made the worst choice about risers and cables. It seems that some1 needs to stop throwing the money and thinking about the health of the rig lol (you have a fire hazzard using that rig, or in the best case, melted risers and/or GPU hazzard). Nice building overall tho.