I'd like to add another MC feat problem to the list that I haven't seen listed anywhere either. When you MC, you typically gain skill training in one skill that's part of the MC class you're choosing. I am playing a Shaman MC Ardent for the extra heal and Diplomacy skill. When I selected the MC Ardent feat in the CB, it then prompted me to choose my bonus skill. The Ardent has 9 class skills and the CB only gave me the option of choosing 5 of the 9 skills...and diplomacy wasn't one of them (diplomacy, bluff and intimidate and arcana weren't available for me to choose). I was still able to choose diplomacy after I typed it in the search box at the top, at which point the option would appear and the other 5 would disappear.
If I was new to DnD or the CB and didn't know what the classes have to offer, then I'm would have missed out on 4 of the 9 choices that class has to offer. I haven't tried other MC builds yet to see if this is a MC feat issue or just an Ardent MC feat issue, but this is another area where the CB fails gloriously.
Edit: Also, I tried reporting the issue to WotC but the help button doesn't work for me, which just irratates me more.