Try this ...
Go to your iTunes media and move all voice memos to an alternate location.
1) I backed up and sync your phone
2) deleted the voice memos playlist in iTunes
3) deselected "include voice memos" under the Music tab
4) clicked "Apply"
5) when sync was done, shut down iTunes
6) disconnected and reconnected iPhone and restarted iTunes
7) reselected "include voice memos" under the Music tab
8) clicked "Apply"
A new Voice Memo playlist will be created with your voice memos in iTunes.
Hopefully the sync will place the new files in the folder.
Now move the previous memos back into the folder.