@berayksl Hi there, to address your questions:

The inconsistent VIO performance between flights

appears the inconsistent vio behavior on multiple arm/disarms is due to the way voxl-open-vins-server re-initializes after a disarm event. Are you still using in the voxl-open-vins-server.conf option "en_vio_always_on": false and "en_auto_reset": true?

If so, the next thing that can be an issue is takeoff speed. To ensure VIO has the correct origin (0,0,0) we have a conf parameter called: "takeoff_accel_threshold": 0.5, This is essential a takeoff detector and is set for a aggressive take off (>80% throttle)

If you are taking off very slow and gentle, it's possible the detector is not being tripped. Try lowering it from 0.5 to 0.3.

The “Yaw estimate error” message (should I be concerned if QGC shows no error)?

If the error doesn't repeat, it's just VIO telling PX4 to reset it's heading and PX4 complains on reset. This can be ignored. BUT if QGC keeps repeating the announcement, you have a PX4 yaw_gate issue--make sure in PX4 the param EKF2_EV_CTRL has the 'yaw' option checked.

And as a sanity check cause you are seeing an R/C issue: goto the radio tab in QGC and confirm your pitch/roll/yaw inputs are calibrated and centered such that you are not sending biased commands.

The drone ignoring RC inputs during the second flight

Are you getting a r/c "manual control lost" announcement in QGC or just lack of control when trying to move the drone? On the former case we have notice users in environments with lots of metal (e.g. warehouse) will have RF interference issues.

At this point, we have numerous improvements in SDK 1.5.0 for Max and it maybe worth the upgrade if your system design allows it. It has improvements with the vio-always-on issues, vio resets, and some PX4 altitude improvements.