We’ve added a number of additional safety checks including the two you’ve bumped into.
The “GPS and AHRS differ by 10.9m” is a check to ensure the EKF’s position estimate is within 10m of the GPS position. Are you using wheel encoders by any chance? I’ve only seen this message once myself and it happened when I think I had wheel encoders enabled but carried the rover 10m away. So if this is the issue we may need to ask Paul Riseborough to look into.
The “Flight mode change failed” error is a result of the first I think. The EKF doesn’t have a good position estimate so it’s not allowing the vehicle to be changed into a mode that requires a position estimate.