Own 10 Power-Ups
The key here is having 1 use available for each power-up. I didn't know that and even posted a comment on the EA support forum. lol
If we define "inventory" as completing the 90 (now 60) uses to permanently have the power-up in our collection, and "own" as having at least 1 use, then the "owning" of them is what needs to happen.
I just went through and used in-game coins to "buy" each power-up in my "inventory". It took me 3 games. As soon as I started that 3rd game - POP went the achievement!
Credit goes to ADDZ777 over on TA.com.