Coupon not calculating all products

I have the following coupons set up:

10% all products

Buy 2 of X product get 1 of X product free

My scenario.

I add 3 of product X to cart - the price is $19 each, the total is $57. The coupon discount amount should be $19

I add the 10% off coupon, the discount amount should be $3.8 (10% of $38). However the discount being applied is $1.9 (10% off only 1 of product X).

Total discount being calculated = $20.90

Expected discount amount = $22.80

Is my expectation of how this should calculate wrong? Or is there some configurations I've not done right?

Thanks.

Hello,

I ran a test on this locally and it worked fine for me.  Is it possible to have a look at your site directly?  If so can you send a private message with temp admin access and instructions on exactly how to reproduce?