When I load new track it changes tempo of current playing track

Something i've noticed all of a sudden

Beat Sync is on Both Decks 1 and 2 - DDJ FLX10

Example of the issue...

I have a track playing in deck 1 = 120BPM

Next track 122BPM I then load into Deck 2 to play next

The track playing in Deck 1 changes to the same 122BPM as the track i've loaded

Whatever track is playing at whatever BPM, I load the next track into the other Deck and it changes the BPM of the current playing track to match the track i've just loaded.

Can someone advise what's causing this please?

Thank you