There are a few reports of the Canon EOS-1D X Mark III going to “sleep” briefly after taking a few shots with the camera. The autofocus points and camera information disappear from the viewfinder and the camera becomes unresponsive for a short time.
There have been a few reports of this as you can see throughout this DPReview thread.
There are also other reports of the camera going into sensor cleaning mode out of the blue and restarting.
Canon Rumors reader Hamilton sent us a video of the issue that you can watch above.
I expect that Canon will address these concerns very quickly.