Accidents encountered in auto takeoff mode

hellow everyone,i have use auto takeoff mode many times.but I found sometimes the throttle value cannot be reached.alawys abolt get a half.so I can only end it,and try again,until throttle work well. and I also found that the plan Turn right before reaching the specified height.Here are my related settings
TKOFF_ALT 120
TKOFF_DIST 200
TKOFF_LVL_PITCH 20
if anyone knows why please help me.