Even if you lose connection as the bonus is beginning, you will always be included in the bonus if you have bonus credits.
If the bonus begins and your device loses connection it may look like your credits seem to disappear. Where are they? They are currently in play in the bonus round you lost connection with, and you will always receive your winnings when you restart the app after the bonus round ends.
If this happens to you frequently then we have some advice:
Disconnection is more likely on a bad connection. It may seem like your wifi or data signal is decent or even strong, but due to the social nature of POP! Slots there is a lot more information sent between our game servers and your device than in simpler slot apps. Playing on the strongest connection possible offers the best experience of POP! Slots so that you can hang on and enjoy the excitement live with the other players at your bank of machines!