I have an iPhone 6s with 64 GB of storage and currently over 28 GB are taken up by the 'other' category. I already tried clearing my safari cache, deleting email and message attachments, offloading and deleting apps, and deleting photos and videos. In fact, when I deleted several large message attachments, the messages storage category went down from a little over 2 GB to a little over 1, but the 'other' category increased by about the same amount.
Apple says 'other' is mostly cache files and doesn't need to be manually cleared, but I have no available storage on my phone and and unable to take photos, download more music, etc. 'Other' is taking up almost half of my storage.
Best Answer
Most of the time you can fix issues like this by backing up your iOS device to your computer.
So backup, then erase all settings and data (Settings > General > Reset) and then restore the backup you just made.
Annoying but easy enough and it usually works quite well.