Found another bug.
When you have all 12skills mapped, there is one skill you can't use at all.
1,2,3,4 = most right line
5,6,7,8 = mid line
Then line at left, 9 and 0 makes two bottom skills then + shoots top skill on most left line. There is one skill what's not possible to use with keypad at all.
To be clear, see screenshot below. It shows which skill slot isnt usable.