Hey there! I can absolutely understand how frustrating it can be trying to add a widget to your home screen, but it just won't work! The first thing I would suggest is to make sure that the camera app is not Hidden. You can check this by going to your phone settings, then "Home screen" and "Hide apps" to see if the camera app is hidden.
If that doesn't seem to be the case, and you have already cleared the cache and data, and force stopped the phone the next thing I would do is check for an update as well as back up your device and possibly try a factory data reset. You can also submit an error report by going to the Samsung Members app > Get help > Send feedback > Error reports.
