have picked up the flask in multiple games now and I'm noticing that aside from the fact it wont activate there's absolutely no way to determine how many, or if you even have any, charges remaining on crystalline flask. It doesn't change in appearance at all in your inventory which can lead to many spammings of the button hoping for a potion that will never come because you're secretly out of charges.

The charges appear on your buff bar.

They're a buff not a stack of consumables in your item window.