Vehicle did not respond to command:MAV_CMD_DO_REPOSITION

After connecting the 2nd FW vehicle to QGC and once I click “positon” flight mode in QGC,the caution comes.
What’s interesting is,after retrying 3-6 times,the command does work!

Contoller:Pixhawk 6c;
Firmware:PX4 1.13.3;
Telemetry:Xbee 3.

Do the two vehicles have different MAVLink system IDs?

To make a distinction between the leader(SYS_ID=1) and the follower(SYS_ID=2)