When the scene is uploaded or bundled the textures that do not tile in the scene are packed in texture atlases to make the scene size smaller. Our current implementation of texture atlasing does not work with tiling. This means that if a texture from an atlas is applied to some object by the material picker in a way that make the texture tile, it will cause visible artifacts. This is what happens in your scene.
The simplest way to overcome it is to construct your material pool such that all the textures there tile, for example by making the rectangles large enough for the tiling to happen. This way, the textures used in the pool will not be packed in texture atlases.
In the future we are going to look for a solution that allows to use texture atlasing with tiling.