It sounds like you're just looking in the wrong place.
Q. I should get back ($2500 - $1555)*0.4 = $378 credit. , right?
A. No. The math doesn't work that way.
$2500 x 0.4 = $1000 on line 29 on form 1040. The $1500 goes on line 20 (via schedule 3). The $1000 comes from line 8 of form 8863 and the $1500 form line 19.
