Yeah - Apple keeps screwing with stuff that can interfere with Android File Transfer, so it can be working, get update, it breaks, get update, it works again - and it's inconsistent across phones.
To make it worse, Samsung keeps borking with part of the MTP handshake message that Microsoft forgives on devices but a straight-up, specification-compliant-only MTP won't deal with. HTC has borked that part too from time to time.
So, often twiddling with the usb connection type on the phone, when available, is enough to kick AFT on a Mac into working.
The latest Linux MTP inclusion (a few years ago you had to add it on, just like you still do on a Mac) seem to be more robust.
Anyway - when you do get AFT working on Mac, it kinda sucks. It's separate from the Finder (aka the Mac version of Windows Explorer) and it has endless look and feel limitations - I promise it's something you wouldn't like on Windows either.
Anyway - there are paid apps that do better, here's one or so I'm told -
http://www.sync-mac.com/mtp-sync.html
And I like paying for a good app as much as the next guy but paying just to move files around irks me so I go for other.
AirDroid is ok, but I've found that syncing what I need via Dropbox or Drive is just far easier, always works, and the only downside is it takes longer for larger files. Which - is why they invented my coffee pot lol, I just go make coffee or something if I have to wait a minute.