Or was that stealth nerfed? Because i did 5 backpacks full of them, found a ton of decent ones, burned through my hordes of ingredients, and ZERO of them turned out to be +5
That’s gotta be over 100 medals. none of them +5 
The chance of a +5 was never large to begin with but with two new masteries worth of skills it’s become a lot smaller.
There’s 48 possible prefixes (see grimtools) and also 48 possible suffixes. That means that there are 48*48=2304 possibilities. Good luck getting the exact combination you want. A full inventory of badges without a +5 sounds exactly like what you’d expect.
So if you can make 100 without a +5 of any kind, but you’re actually hoping to get 1 specific +5, that’s 10s of 1000s of rolls… that’s ridiculous.
I’ll settle my for my 2s and 3s lol. Before AoM in a full bags batch I would expect to get 2 or 3 +5s.
Before AoM there were 32 possible pre and suffixes, making for a total of 1296 combinations.
Badge of Mastery was, with those stats, in my opinion barely worth it. Now it’s just trash.
Don’t I just love abbreviations… 
Seriously, I would have never guessed that BoM means unless someone actually spelled it out.
I never found more than +2s, but I am guessing the +5s only roll above a certain level on Ultimate or so…
Level or difficulty has nothing to do with it. There’s 2304 possible combinations and only 48 of those are +5. So, just really poor odds 