Thank you for your reply. Its working now

@Uros . .

@vmassague Hi, I am pretty much doing the same thing and I faced a similar issue with you. have you solved this issue? https://forum.modalai.com/topic/919/using-motion-capture-systems-optitrack-for-position-estimation/2?_=1656684369036

Nevermind, apparently I looked in the wrong places: https://dev.px4.io/master/en/ros/external_position_estimation.html has the answer: EKF2_HGT_MODE must be set to vision to use the voxl odometry instead of the barometer. Closing this.