Can Not Transfer Voice Memos
I'm assuming you are attributing the 5.93GB to voice memos? That would be about 75 hours of memos. (They use about 2MB per minute.)

"Other" in iTunes is a large catch-all that includes things like mail caches, Safari browsing data, iTunes streaming caches, and more. The best way to identify how much space is being used is on the device itself - Settings app > General > Usage.

As far as the Voice Memos not syncing, check on your hard drive under &lt;your username&gt;/Music/iTunes/iTunes Music/Voice Memos and make sure they aren't actually there (and just the playlist is missing). If they are not, uncheck the Sync Voice Memos setting, apply your changes, then reboot your phone (hold Home + Sleep until the Apple logo appears) and your Mac, then re-enable the setting.