Stamina bug (incorrect math)

Stamina isn’t working properly;
I had 23 Stamina left
I watched an ad for another 30 stamina (53 total)
I then looted stages 3-10 & 4-10, each of which has 5 challenge opportunities per day at a cost of 5 stamina per challenge (50 stamina used)

But after the looting, I had 18 stamina left

Thank you for letting us know. We’ll investigate this!