Hi,
you do not miss anything. but your concept about odoo's variant is different.
when you give variants like in your screenshots odoo take it as only one product with different attribute.
to get different variants in your case, you have to give the variants like the following.
and also note that odoo creates 4 variants for this settings.
you can't create 2 variants like one product with weight 75 gm and 48x75 size. second product with weight 30 gm and 12*12 size. this is not possible in the case of odoo.
Maybe you have only 2 products. but in the case of odoo, you must have to create 4 variants.
Thank you.