Pressing Play on one CDJ 850 stops play on the opposite one intermittently! (Using Rekordbox 5)

Does anyone know if this is a common issue with a common fix? This happened 4 times in a live set at the weekend for the first time, music just stopped completely on the other deck when doing as described in the title - until you press play on it to resume the stopped track!

Using Rekordbox 5.8.5.0001

Windows 10

CDJ 850

Another I've noticed is that audio outputs are reversed for some reason using the Pioneer ASIO Driver.