Aim 9x not showing up when I create a new mission

[Skwirl865]

I have a practice mission for bvr but it’s on the caucuses map. I want to put it on the marianas map and don’t know if you can change terrains on an existing mission so I’m trying to create another one on the M-terrain and when I do, I don’t have access to the aim 9x in payload. 
it’s there on my original mission on the caucuses but not in any new mission I make. 
anybody know why?

[Skwirl865]

All of a sudden it started showing up when I changed coalitions