There's also the "pavlis" recipe, or simply the potassium bicarbonate mix:
Make a concentrate of 10 grams per 100 mL, then use 1ml of concentrate per 1 liter.
Be sure to keep the concentrate in the fridge to slow down the growth of any civilizations, though. A 100ml batch lasts me about 6 weeks at roughly 4 shots a day.
I ran into this exactly, but it turned out to be device compatibility. I could never find it in the play store on the (x86) Chromebook, while it always showed up as you'd expect on the arm android.