This is because you are forcing the tile to be 450 in width which is basically the full width of of the theme’s content area. Tile Plus was designed with the goal of be a tiled display rather than a full width display. Setting it so wide basically removes the responsive support. If they were tiles as designed, the responsiveness would be the number of tiles per row would change to accommodate the theme’s content width of whichever device the page was being view on.
Now, all that said… tthe them does not seem to be responsive any way… at least in my quick test on a couple devices. If the theme is not responsive, the template can not be because the template can only react to the content width that the theme sets for various device display widths.
Hope that explains it clearly enough without causing any additional confusion.