Hi Loukos,
what FW version was installed on the BAT when this occurs ? I guess this is refering to one of 3 known Problems:
1st Housekeeper Update ("erratic stick swapping"
2nd Problem with inkonsistent calibration data
3rd Problem with inkonsistent model data in the flightcontroler
It is like that 1) and/or 2) had happend to you.
best regards
Thomas