Anytime I take off the phone or put the gimbal in standby, I have to recalibrate when I connect it back on. When I remove the phone, I keep the magnettic clamp on the phone so that it stays in the same position.
I am using iPhone13 without cover. I have ensured that the dot on the clamp aligns with the dot on the gimbal and followed instructions for calibration.

Once I calibrate, the gimbal works fine if I hold the trigger button to lock. But if I release the trigger hold and use it in any of the other modes like Follow or Tilt lock without the trigger button lock, the horizon is keeps going off and I have to recalibrate every few seconds.

Hi, Reachbgk. Thank you for reaching out and we apologize for the inconvenience. Please follow the troubleshooting steps below to fix the issue:

1) Update the gimbal to the latest firmware version.
2) Complete gimbal auto-calibration.  
3) Complete horizontal gimbal adjustment.  
4) Restart the gimbal and try again.
5) If the issue persists, perform the following:  
a) If the magnetic phone clamp is used, enable the phone’s level function to check the tilt angle.
iOS: Enter the built-in Measure app.
1) Check the tilt angle and correct the position of the phone. Take the horizontal screen placement of the phone as an example:
a. If the level value is negative, it indicates that the center of gravity of the mobile phone is on the left, and the mobile phone needs to be pushed to the right until the value shows 0°;  
b. If the level value is positive, it indicates that the center of gravity of the mobile phone is on the right, and the mobile phone needs to be pushed to the left until the value shows 0°;  
2) If it is found that the tilt angle is decreased after adjustment, perform Horizontal Gimbal Adjustment via DJI Mimo to correct the motor angle.  
*As the mobile phone's gyroscope may have certain deviations, the displayed angle is for reference only. Please try to compare objects with the grid lines of the camera to determine the tilt situation.
*When using the magnetic phone clamp, please remove the phone case. As the case material is relatively soft, it may easily cause the phone clamp to be tilted at a certain angle.

If the issue persists after following the steps, please let us know. Thank you for your understanding and cooperation.