Quad in Mission Mode Circles at Some Waypoints

Hello

http://logs.uaventure.com/view/hdz3nsRfQaVE8kMyRSfESB

This is the link for our flight log. In the log, you may see from the map that our quad circles around certain waypoints, and then after 4-5 circles, it decides to hold the waypoint and then continue to its mission. What may be the cause for this kind of behaviour?

Deniz