This tends to happen when there isn’t enough room on your device. The priority for your mobile device manufacturer is that your device continues to run, so if it is running out of space it will delete something that won’t disappear forever. A great example of this is magazine issues, as they are always available to you to download from the cloud. Great in theory, as it would be worse if your phone just started deleting precious photos that hadn’t been backed up, but annoying when you are trying to access your magazines, for sure!
The magazine app itself doesn’t take up a lot of data, but if there isn’t a lot of space the issues will be deleted.
Check the storage available on your device. For most people, photos are the biggest culprit. Backing up to a storage device and making some space will rectify the issue.
Android phones vary, but the process should be similar to this. Click on the image to view a larger version.