Hi. I am having the same issue too. To be more specific, my Mac can see an Arduino UNO however the nano only let's me see the following:
/dev/tty.Bluetooth-Incoming-Port
/dev/cu.Bluetooth-Incoming-Port
/dev/tty.Bluetooth-Modem
/dev/cu.Bluetooth-Modem
If I plug in the Uno, I see the same but augmented with the USB choices (correct).
I have tried all the common problems solutions (new cable, plugging in again etc) but nothing works.
Did anyone ever see a solution for this?