Missing crafting materials

I bought to 20 apex packs for $10 in the store for crafting materials (because I was close to crafting a skin I wanted) and was at 3,950. After open my 20 packs I got 600 more plus some gray rarity materials. Once I left the screen where it shows your rewards my crafting materials went down to 3,160. I don’t know what could have caused this but it’s very annoying.