Good afternoon Spiral Knights!
I was doing the rank mission 'Frostifur Fandango' (4-2) and on the second floor of the mission I experienced a bug. I was running around in a loose circle while planting 1* splinter bombs around a group of Frostifurs. Suddenly I couldn't see my knight, he seemed to have "sunk" into the ground and he ran to the left (I could tell because my camera moved that way). When he reached the edge of the field I could see part of his head, and his arms and legs moving as he continued to try to run. The rest of his body was obscured by a bush. I couldn't get him to move, stop running, turn in any other direction, put up his shield, etc. Yet the Frostifurs could still attack and killed me.
I thought respawning would solve the issue because the fainted knight was on top of the field, but as soon as I did so I went back to running in place to the left. After I died again I decided not to waste the last of the mist and I went back to haven.
It wasn't until the loading screen came up that I figured I should've taken a screenshot, so I don't have that. 8(
This is really really weird. I've never experienced this. So did your controls go back to normal in Haven?
Next time, take a screenshot if you can and press F2. (This sends the developers a log file of what is going on along with a message you write, so it should help them to sort the issue out.)