Qplane 4.0.7 compass issue

After many tune I set compass external only away from pertubation (in the front of canopy, far from battery’s, power cables, far from qmotors, and far of prop motor that is on the back of canopy.) i disabled onboard compass (cuav x7)

I get perfect results with perfect compass on qmodes in flight (no ekf errors) but when I switch to plane mode in flight compass get more than 80deg error….

Is like the plane recalibrate compass in flight when in plane mode, it’s dramatic.

Why it do that, how to correct this?