Rekordbox "Loopin consistency"

I've bought a ddj-400 few months ago. For my transitions from one track to the next one, at times what I do to extend and manipulate the incoming track is to create a loop from 1to 4 bars depending on the following track. Well, for an unknown reason, it's been a week since the last time I could do "such trick", where you leave the next track "looping" repeatedly up until I decide to release it, keeping both tracks playing perfectly beatmatched, even when the loop from the upcoming track restarts to its initial position. Using this technique, It is a very easy way to bring the next track, knowing that it has been beatmatched and looped repeatedly. 

The problem happens once the loop from the upcoming track finishes its course, because eventhough both tracks are synced and beatmatched, once the loop from the following track reaches the end of it to restart all over again, the syncing and beatmatching of both tracks loses its parity and no longer both tracks played in sync and beatmached, being  the  upcoming track the one losing a slighly tempo that makes them sound awful.

I tried by resetting to default the different settings, but it doesn't fix the problem. Any recommendation? I used to be able to mix doing this technique but I can't do it no more.

Any suggestions would be appreciated...