XDJ-RX2 Master BPM gets locked to one deck

I have noticed occasionally in the middle of my sets all of the sudden the master BPM (the one highlighted orange on the display) gets stuck to one of the decks. It has happened to both the left or the right. So then for the rest of the set every song I play is stuck on the BPM of the left (or right) deck. 

For example:
The left deck gets locked at 145 BPM but audio is playing out of the right deck (at 145 BPM). When I load a new track onto the left deck at 150 BPM, the right deck then just jumps to 150 BPM and ignores the right deck's BPM setting.

Is there a feature/setting I am missing. It doesn't seem to be automatically switching back and forth .