There are some M11 freeze issues floating around, and I also experienced them myself. I had two different freeze types that don’t seem to be related. In one case only the Visoflex 2 EVF eye sensor worked to turn the EVF display on / off. No button, including the power switch worked. Removing the battery fixed this. The other freeze or rather non-function I often encounter is after turning the camera off (in reality wanting to turn it on), then in an instant realizing my intention and turning it on again. If I do this too fast the camera just seems to ignore the power on. If I wait for a short amount everything is fine.
This is nothing really worrying, and something one can get used to, plus the latest firmware already fixed many freezing issues, so I think there is a fair chance of also fixing those in an upcoming firmware update.