Please follow the basic troubleshooting steps below:
1- Try updating your device operating system and deleting and reinstalling the app, making sure to log back in with the same account so you don't lose your progress
2- If the issue persists afterwards, close all the apps opened in the background and make sure you're running on full battery
3- Increase your device's memory / RAM
To increase the RAM of your iOS device:
http://www.iphonehacks.com/2016/02/instantly-free-up-ram-on-iphone-to-improve-performance.html
To increase the RAM of your Android device:
https://www.androidpit.com/increase-phone-ram
Apps like CleanMaster can also help do this.
If that doesn't help, please contact our support team from the "Help" menu in the app letting us know what you have already tried so far and please send us a screen recording of the issue so our Quality Assurance Team can have a look into this for you and reproduce it on their testing devices.
This is how you can take a screen recording on an iOS device: https://support.apple.com/en-gb/HT207935
This is how you can take a screen recording on an Android device:
Please download a screen recorder from the Play Store if you do not have this function in your device. We recommend the DU Recorder for this but any other screen recorder will work, just ensure that it is one of the free ones available or take a video of you playing Peak via another device and send the video to us.
If you are unable to provide a screen recording please provide us with screenshots instead if the problem is clearly visible via screenshots.