Trouble connecting to LG phone with adb (Mac OS X 10.7.5)
I tried all of the connection types (charge, MTP, PTP) but perhaps not "Internet Connnection, modem"? You can change it by pulling down the system-wide drop down menu and touching "USB connection".
This is how I fixed it, but I thought I'd tried this already, so I can't guarantee it wasn't this in conjunction with one of the things done above.