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.
000E0CDB), then try clicking anywhere until it's gone. Otherwise it'll turn off clipping for that target.
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
tcl, and while collision is
off, come across an enemy and try and engage said enemy. It will not work for obvious collision detection off reasons.
Then I turn collision
on, kill the enemy, while
tgm is in effect, then
tcl stops working for me.
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.