V Tail Crashing

Need your help to understand the logs. We are flying a custom made fixed-wing with an inverted V Tail configuration. Since yesterday I am getting this problem of the plane crashing down in auto mode. The bird starts rotating like a chopper on its yaw in a circular pattern and comes down. Yesterday it crashed after flying for more than 45mins and came down spinning from an altitude of 400m and today it crashed with the same behaviour in less than 5mins. It doesn’t take manual control or any operator input once it goes into that spin profile.

I am attaching logs for your reference.