Arducopter 3.6.12 Hexa swings up on landing

attached is a log of a flight that was mostly normal. But when the Copter was in a descent (PosHold) it started to swing up for no apparent reason and could only be stabilized by changing the mode to AltHold. I see in the logfile at the appropriate place big differences between DesRoll and Roll, but no error messages and can’t explain this to me. Maybe someone of you can have a look at it, thank you very much!

Hard- and Software:
CubeBlack with Copter 3.6.12
SF11 Lidar
Slamtec A3 Lidar (not activ for communication reasons)
Tigermotor MN701 with 24" Folding-Props and Alpha ESCs