I know, I should use the TCL command. But sometimes it works, and sometimes it doesn't. When it works, the console responds Collision -> Off (or On), when it doesn't work, the command returns nothing.
Make sure you have nothing selected. If there's a string at the top of your command line interface (e.g.
Source: Skyrim Console commands
This has happened to me, and I will try to relate my experience with the PC game console and the steps I took.
If I use
Then I turn collision
Then I have to save the entire game and exit to desktop, and restart the game. Then reload the most recent save.
This is in Steam offline mode though which should not matter.
Without speculating on the actual code, it seems to be an issue I think with the console collision on/off mechanism.
Hope this helps.