In the first instance, please could you try the following?
Uninstall the app from your device.
Download the latest version from your app store. You can restore your purchases by going to the app settings and then selecting 'restore purchases'.
If that does not solve the issue, please email the following information below to help@studycat.com so we can us investigate further.
The app name and the version number: for example, Fun English 21.1.0 - you can find this by going to the settings area; the version number is listed in the bottom right-hand corner of the screen.
Your device and operating system: For example, iPhone XS using iOS 13.0.4
Description: A brief description of exactly what is happening.
Video or Screenshots: If you could also provide screenshots or a video of the error happening, it may help us to identify and resolve the issue quicker.