Y-Axis Shift?

Every now and then I am getting this weird Y axis shift on my M5C prints. The printer makes a kind of straining noise very early in the print, and it completes mostly fine, but a couple of centimetres higher on the Y axis. As you can see in the image, part of the brim was just printed into thin air. So far this hasn't messed up any prints, but obviously something is wrong.

Every now and then I am getting this weird Y axis shift on my M5C prints. The printer makes a kind of straining noise very early in the print, and it completes mostly fine, but a couple of centimetres higher on the Y axis. As you can see in the image, part of the brim was just printed into thin air. So far this hasn't messed up any prints, but obviously something is wrong.