A texture that just applies a solid color usually indicates that there are no UVs at all, which seems to be the case on your latest uploads. It just applies the color of the [1,1] pixel everywhere.
In general, I would always recommend OBJ over PLY when uploading textured models. We have some known problems with textured PLY files (unrelated to this issue).
When exporting from MeshLab, I've found that you need Wedge TexCoords, rather than Vert TexCoords