In most cases, if the app won't start or it loads inconsistently, it's because the device (typicaly an iPad) has little to no storage left on it. The solution is simply to remove whatever you don't need from the device e.g. any videos, photos, large attachments or downloaded programmes from apps such as BBC iPlayer. Make sure 'Recently Deleted' album on your Photos app is emptied.
To confirm whether insufficient storage is the issue
If the difference between the amount used and the total storage available (typically 64Gb) could be described as 'tight' then this confirms the limited storage factor that's stopping your app from running.
Apps
You may need to delete an app or two that you no longer use to free up space too.
To do this
