Djm Rec problem

Djm rec problem
When I plug the USB lead into the USB port on my djm450, djm Rec wont recognise the mixer even though my iPhone device is being charged from the mixer. In settings audio input says audio jack when it should read lightning cable. Send/return on/off button won't go blue either. I've recorded multiple times with no problem, this is the first time this has happened. Any help please?