As the title says, I use a mac and I have been unable to use both my M7 (After 4.4 Update) and my M8 on my mac. To be specific, android file transfer never sees the phone. Occasionally when booting my phone up when connected the manager pops up with a phone could not connect message, but it has never worked. This is isolated to just HTC phones for me, I verified my setup is fine with a Note 10.1 2014 (running 4.4.2), Nexus 5 (4.4.2), and a S4 (4.2). All of those connect fine.
I know there were some threads about HTC breaking something but I haven't seen a fix yet. Is there one?