I have just come upon this bug, and the "full" option when turned off does not seem to work, to get it to work you have to search all multiplayer hosts, and once it is done, turn it on, and then turn it back off. Not sure when this happened but it doesn't work first time around.

I think it's because it does show you hosts that aren't actually full but they have enough people in the join queue to make them full.

So - 45 people + 2 connecting - not really full but displays 47/47.

This is because the master server doesn't know how many people are in the join queue, and LFS doesn't apply filters to the list of games received from the master server, as it assumes they are already filtered.

In a way, I think the "full" filter might be a bit useless and better just deleted. There aren't usually that many full, there's usually a spectator slot or two free, or if not there soon will be. It's not a useful filter like the "empty" one is.