ATF is not working on iMac/Yosemite 10.10.3. The target mobile is a Samsung Galaxy Ace 4 with Android KitKat 4.4.
I have tried all the workarounds i.e. reloading ATF, changing USBs etc. The Apple software systems information tells me that the Android is connected to the USB 3.0 Hi-Speed bus and the Galaxy tells me it is connected as a media device.
But ATF tells me "Could not connect to device". I have tried tethering the phone to the USB but no difference.
(Bluetooth is working OK but too slow for file transfer.)