You sure they were set items? I'm not sure if these are exceptions to the rule or, again, if I'm missing something (maybe it's not supposed to work with set armor? doesn't really make sense if the original set pieces are all wearable anyways, and it works with my rare mojo --> set mojo...), but these armor pieces are all set items that I got the plans for post 2.0 -- tried with a helmet as well and it didnt work but I salvaged it so I can't grab a screenshotI just did a bunch of crafting for my monk 2 weeks ago and every single item that I crafted was unlocked for transmog. So not entirely sure what you're referring to when you say what you and some others have tested, could you be more specific? Did you not get the transmog at all? Maybe you already had the transmog? My testing confirms what is written in the FAQ, and I believe everything else appears to be a bug, but I'm not aware of such a bug. If you could point me to posts/threads of such observations or maybe be specific as to what item exactly you were crafting to get the transmog design, I'd be happy to include those bugs/exceptions.
Showing that the option isn't there (moused over to show that it's account bound and crafted by me, also shows that I'm trying to transmog my normal helm -> normal helm, not voodoo mask etc) and they are all post 2.0
Thread with a few people having the same problem
edit:Maybe I should have posted this in some sort of help forum instead? Oh well...