For other mobile players, how do you actually finish an ad to claim the reward??

For context, I haven't been getting ads in games for ages, and while that's good most of the time, my progression in Idle Slayer has been super slow.

I recently found out I was on a private DNS, so I turned it off and tried to get some of them sweet silver random boxes.

By the time I get to the end of an ad, the only way it will let me finish it is to go to the play store, but this makes the game reset when I go back on to it, and I don't get the reward, it also makes me lose out on Chest Hunts if I try to get the shield.