Can't mount filesystem from LG-V20 on MacBook
I'm sorry I don't have a solution for you, only a small clue.  I have the same issue with my LG V-20 and Windows 10 on a Surface 3.  I run diagnostics on Windows 10 and it tells me that the V-20 does not support USB3. Since the only kind of port on the Surface 3 is USB3 I'll need to try another computer.  (I'm on vacation and have only the Surface with me so I cant try this out right now.)  If your macbook has USB2 ports you might try these or if not, try an older computer if available.