Took off from an open space parking lot today as I always do since the building I work on is next to my apartment. A nice sunny day and the flight was smooth with altitude of 175 feet. Turn the drone to different direction and suddenly noticed a shaky camera. And weak transmission appeared and before you know it, loss connection. Hit Rth but no response. And all of a sudden, the drone went up to maximum altitude 394 feet and just hovers. Good thing it’s in line of sight. Hit the Rth again and still a fail. GPS came back, cancelled rth and gained control. And brought her back down safely. Made me worried momentarily. Could have been strong magnetic interference? Imu calibrated and firmware up to date.