custom Product Thumbnail Size [MarketPress]

I line up products using [mp_list_products] and set Product Thumbnail Size 200 x 200 in Product List Settings

I uploaded 2 different images, the size of the one is 425 x 425 and the others is 238 x 228 as test

as a result, 425 x 425 changed into 200 x 200 correctly but 238 x 228 changed into 200 x 191

I think they keep aspect ratio correctly but I want all of thumbnails into same size

*they all changed into 150 x 150 correctly if I choose "WP Thumbnail size" but not at WP Medium size

any help?

thanks in advance