I can walk through certain things in the level editor.

I don't know if this is just a bug or is there an option to stop it? I've been making my map for about 7 hours and only certain objects I can walk through, any help would be appreciated, thanks.

EDIT: Found out the issue, it seems to bug out once placed, if you save and reload the map it works as intended.

Thanks for the help! I had the same problem. Also i realized, that you can look under the roads textures of selfmade roads... pretty ugly

There's a way to fix this issue without reloading the map:

If you go to edit the object, there is a box called "enable physics" which is on by default. Just toggle it off and then back on (this will sometimes give an error which can be ignored) and the object should work as intended. You can also apply this to a selection of objects, though it seems to sometimes move/rotate the objects which is unwanted so be cautious and remember to save often.