Hey, I hit exactly the same issue - and think I've realised the WHY so created an account just to post here...
I know all the above posts are old but this page is the first hit I got from google.
Take a look and the "required components" in the above screen shot - it shows a list of item compoonents AND the LESSER version of that item.
When you craft a lowlier component, you don't get a version of that component appearing in the set of requirement icons.
So for these crafts, you're not crafting from scratch, it's re-crafting with an existing item.
The completely separate "Upgrade" tab makes this very confusing!
This explains all the weirdness reported above around the stash - you've got to get the lesser version out of your stash and into inventory to craft with it.
The game does try to help you by asking "Are you sure?" whenever you're about to sell or disassemble an item that can be "recrafted" in this way.