Tracks are not registered in the HISTORY.

It could be one of the following three cases:
1. There is not enough free space on the device.
2. The device is write-protected.
3. The track has been selected for 60 seconds or less. (The XDJ-AERO is designed so that tracks are stored in the HISTORY when they are selected for more than 60 seconds. They are registered even when operations other playback are performed or when in the in the pause mode for more than 60 seconds.)