I have not tried reinstalling .400 and can see what happens.
Did you have this same yaw drifting/glitching issue?
Doubt it will help as the issue is confirmed by DJI support to have been introduced in .400 and that a fix is pending F/W release.
You got my hopes up, but unfortunately it did not help.
Mine's had a yaw drift since the last version (.400) and many others are complaigning and have flight log data.
DJI has acknowledged the issue but has not released an update for over 3 months.