Pitch always turns negative by itself

Hello,
I've got a strange problem with my mixvibes software. After loading a new song to my right deck, the pitch always turns slowly to the maximum negative value, so, when the range is set to 10%, it is moving down to -10%, when set to 100%, it moves down to -100%. The song on the left deck is the same, so the bpm is the same and it can't be a problem of autosync (if there is such a function anyway).
Is there another option, that could turn to this problem? I don't see any activated setting, that seems unfamiliar, it's really frustrating.
Thanks a lot for your help!
I've got a strange problem with my mixvibes software. After loading a new song to my right deck, the pitch always turns slowly to the maximum negative value, so, when the range is set to 10%, it is moving down to -10%, when set to 100%, it moves down to -100%. The song on the left deck is the same, so the bpm is the same and it can't be a problem of autosync (if there is such a function anyway).
Is there another option, that could turn to this problem? I don't see any activated setting, that seems unfamiliar, it's really frustrating.
Thanks a lot for your help!