Ecl EKF2 estimation help

I’m currently integrating GPS NMEA protocol by indoor beacons with 4cm accuracy (marvelmind).
I’ve mounted everything and px4 gets the nmea setences that gives 3D position.
Innitially I was geting some 2D position drift in hold mode and wrong altitude, but changing some parameters I fixed the position but the altitude is wrong.
When I check the log of my flights, the variable gps_global_position-> alt is really different from vehicle_gps_position-> alt, while the vehicle_gps_position has the actual correct values ​​from altitude, given by the GPS.

I’m thinking that this could be a problem related with estimator, since the accurary of conventual GPS isn’t that low, and with that, I need to change some of EKF2 parameters.

Is there someone that can help me with this?