[NTG-context] align question

On another matter, I'm having some alignment issues. Consider the following code: \starttext \startformula \startalign[n=4,{left, middle, middle, middle}] aaa&b&cccc&d\\ a&bbb&c&ddd \stopalign \stopformula \stoptext Compile this and you will notice that the alignment parameters {left, middle, middle, middle} are ignored. And you can change these to anything else (left, middle, right), with absolutely no change. Any idea what is going on here?