I uploaded a mission to the vtol aircraft, but when it gets to the altitude where it should transition to fw, it drifts slowly instead and then triggers failsafe/RTL.
More detailed issue report here: [Bug] HITL Standard VTOL Aircraft doesn't transition to FW Mode and triggers RTL · Issue #24682 · PX4/PX4-Autopilot · GitHub
I found that this was caused by a mismatch between the values for actuator configuration loaded into QGroundControl.
When the UAV is loaded into HITL, it is missing a motor assignment for the 5th motor that is responsible for propelling the UAV forward.
To correct this, go to Vehicle Setup > Actuators > Geometry > Motors. Increase the number of motors from 4 to 5.
I am unsure of what specifically causes this.