discoveries are random.
you just have been unlucky.
it doesn’t matter where you make the pot/elixirs, you have the same chance, if you’re in the bank, in town or where ever.
if you X-mute every day, you will eventually discover a new X-mute.
the more pots/elixirs you make the better chance you have to discover something.
I am elixir spec, and I have proced extra's on my flasks before :)
one thing to note about specialty’s. you only have to do one quest once. I wanted to be Elixir spec, but my Hunter Alcimist is perma parked in IF. he doesn’t run dungeons anymore, so, I had to turn in the 4 primal might’s to get X-mute spec. then I paid the fee to drop that, and was instantly able to become Elixir spec W/O doing the Elixir quest, because I had done the X-mute quest already.