121 mic not always on the list

Why is the 121 mic only available with a few cabs?
Am I missing something?

If the IR wasn’t recorded with that cabinet, it won’t be available to choose simply bc that extension of the IR wasn’t made. As a guess, I think that’s what’s happening. If you notice that other people have access to the 121 on the same cabs that you don’t, then it’s a really weird issue that you’d need to contact support about.