Why does my Phone (iPhone7) say storage full when the settings > Storage > 'visual data representation' only has 16.3 out of 32 gigs used?

Why does my Phone (iPhone7) say storage full when the settings > Storage > 'visual data representation' only has 16.3 out of 32 gigs used?

Because iOS is a buggy piece of ****. I had to factory reset and restore multiple iPhones from clients just so unused space in the gigabytes did actually become available again.
Do yourself a favor and get an Android phone next.