The Images below will best describe what im talking about
In Editor, The Paint Object works similarly to one way arrows, I applied steel here but I also used terrain with "allow one way" unticked
(https://cdn.discordapp.com/attachments/249723222155591690/1039113839507144785/image.png)
But in game, Paint Ignores this and overlays anyway
(https://cdn.discordapp.com/attachments/249723222155591690/1039113839851098162/image.png)
Paint objects are not one way arrows and therefore are not expected to be affected by this setting. Only on terrain (for non-OWA objects) was not affected either IIRC.
If the editor is applying this setting to them, that's a bug in the editor. I have relabelled this as an editor bug accordingly.