In Logic you have the option to use 2 different modes of MIDI operation
OMS or AMT
the AMT (active midi transmission) is a proprietery MIDI format that is used only by EMagic products that gives air tight Logic Midi timing..
OMS is the normal standard midi processing for a MAC

You must put the AMT 8 in AMT mode by going to:
Settings > Midi interface communication > and check and see if
the OMS available button is checked... if it is please UNCHECK it
When you uncheck this box , this page changes to reveal 3 different connection options..
"Unitor family" should be chosen in communication 1
if you had more than 1 usb mdi device you could chose communication 2 and 3
Once you chose this option the AMT8 is now ready for MIDI assingment