Any idea why Taiwangun won't let me order this replica?

I'm trying to buy the Noveske 10.5" Gem III Shorty 300BLK from Taiwangun and every time I go to checkout I'm greeted by an error message that goes:

"Selected items cannot be bought with delivery to:

Noveske 10.5" Gem III Shorty 300BLK AEG Rifle - Tan \[EMG\]

Item has been deleted from your shopping cart"

I understand the error being that it can't be delivered, but it says it's being delivered to nowhere. I live in the US, have prior purchases with Taiwangun, and it works with other products just not this one. Should I just reach out to u/taiwangun_com or has anyone else had this issue?