Solo M8N Coordinates and Pix4D

Hi there!
I own a Solo with Sony QX1 and M8N from Drotek for photogrammetry.
In Pix4D, when I inject geotagged pictures, I always have an offset in altitude, it looks like the coordinates format is not good. I can verify it after the add of with my ground control points and the GPS position vs the calculated position of my pics.
Is there a way to choose the coordinates format of the GPS output?
If no, what is the altitude reference (ellipsoid, egm96, amsl…)

Thank you!!

Corvus Monitoring