Problem

When the drone starts gaining altitude, the VIO becomes unstable and the drone quickly becomes impossible to control manually. During hover close to the ground, the drone is relatively stable, but once altitude increases:

• Position estimation starts drifting
• list itemYaw estimation becomes unstable
• list itemHeight estimation errors appear
• list itemManual control becomes very difficult or impossible
• list itemPX4 eventually reports preflight or estimator failures

Current Setup
Hardware:
VOXL2
Starling 2 platform
Indoor environment
No GPS
Manual flight mode
QVIO enabled

Environment conditions:

Metallic industrial environment
Low texture surfaces
Variable lighting conditions
Errors observed

We frequently see:

Preflight Fail: height estimate not stable
Preflight Fail: Yaw estimate error
Preflight Fail: Attitude failure (pitch)

Additional Notes
We are NOT using QGroundControl during flight
The issue appears mainly when ascending
Near the ground the drone behaves much better
The instability increases progressively with altitude
It feels like VIO loses enough visual references when moving away from the floor

Questions
Is this a known limitation of QVIO / tracking camera placement?
Could this be related to insufficient floor texture?
Are there recommended tuning parameters for altitude-related instability?
Should we reduce dependency on QVIO and fuse additional sensors?
Would adding downward lighting or a ToF sensor significantly improve stability?
Is there a recommended EKF2 configuration for industrial indoor environments?