Rising Altitude by reaching Mission Waypoints

Hello everyone,

i need your help by analyzing the graphs and copter behavior.

i build a Hexacopter with 4000g (Tarot 680 frame). In manual-mode it flyes well but if i start a mission it occurs sometimes that the copter tries to reach a mission-waypoint (nearly no wind) and than rapidly goes higher and higher. In appendix you can find the log files. In the x-axis (21:40) you can see clearly this behavior. The copter gets very unstable here. I tried to reduce the thrust in position mode (with my taranis x9d), but this was also not working good. The copter was jumping here.

Rising ALtitude Log File

Which parameter should i change to get a more stable behavior.

Thank you for your help.