QUADPLANE + Pixhawk4 Altitude error and auto mode interrupt

good evening everyone,

I have a 4 + 1 3D printed quadplane, a Titan Dynamics Buzzard which has a Holybro Pixhawk 4 as electronics, but I have a problem in the auto flight mode and in maintaining altitude, I attach the flight log and two videos in first and third person of the AUTO flight.

As you can see, at waypoint 9 the aircraft stopped completely, going into qloiter mode, and from that moment I took it back to land it. what do you think could be the problem? thanks so much to the whole community

LINK to telemetry and video: Log file and video of flight - Google Drive