Most of the time iPhone users will see a spinning wheel between 3-10 seconds if they get a push notification to their phone from Lightcatch.
Sometimes during peak usage the wheel can spin for over 20 seconds. If the spinning wheel is over 30 seconds close the app and re-open it.
Apple has this really simple visual guide on how to close an app on any model on Operating System of iPhone at https://support.apple.com/en-us/HT201330
On an iPhone with Face ID: Swipe up from the bottom edge and pause in the center of the screen.
On an iPhone with a Home button: Double-click the Home button.