Catapult take off altitude lost

Hello I am developing a catapult type fixed wing airplane.
When taking off with a catapult, altitude information is not displayed.
Is there a reason, or is there any information I can refer to?

No idea, please provide some details such as a picture or a logfile or a video, anything that might help identify the issue.

The log looks fine to me. What am I supposed to see that is wrong?

Thank you for your reply.
Take off the plane using a pneumatic launch pad.
Altitude information is not displayed on the QGC at the moment of launch.
What is the reason for the missing information?
It doesn’t happen every time, it happens occasionally.

Maybe related to the EKF instance switch, which in turn may be caused by the high acceleration at takeoff?
You could try if vanishes with EKF2_MULTI_IMU set to 0.

Further, it could potentially make it clearer what you see if you also post a screen recording/video of the the QGC screen when the failure happens.