If you have created a user mapping and not saved it or have an auto saved mapping, sometimes you may get whats know as a Midi Conflict.
This means you can hit a function on say a Sixty-Two like the Mic ON button and it sets of an SP6 sample, or you press Flex FX and it activates a loop etc.
To remedy this you will need to rename your MIDI folder in the _Serato_ folder.
If you have saved mappings you can copy them over after.
Follow these steps:
Close Serato DJ
In finder go to you Music folder and find the _Serato_ folder e.g. Username/music/_Serato_
In the _Serato_ folder you’ll find the MIDI folder
Click on the name of the folder and rename it to MIDIOLD
Open Serato DJ (this will create a new MIDI folder)
Connect your hardware and you should not have any conflicting midi information now.
If you have a saved mapping you can copy it over from the MIDIOLD folder to the newly created one and paste it in the XML folder inside the new MIDI folder