X7 blur & smear at ISO800 or higher - unusable photos

Hi all,

We have an issue where our X7 is completely unusable at any ISO setting of 800 or higher. The photos are blurry and look to have a 'smear' like effect all over them. DJI claim this is high iso noise but I dont think thats correct, as there is no 'noise' present. Anyone else had this issue?

Photo below is ISO200 on left and ISO800 on right. Note the edge of the building and the antenna? Its almost like an anti-aliasing effect.