Transmogging to Primal Molten Breastplate Not Possible?

Hey there - I’m wanting to transmog my chest on my warrior to the Primal Molten Breastplate, but it does not show up when trying to do so. It shows in my collections and says to visit a transmogifier to apply, but it does not show up there. Are these not possible to tranmog to, or am I missing something? I was thinking that was the case, but you can transmog to the primal moletn sword, so I feel like I’m just missing something.

Thanks for any help!