Placeholder is not working.

If I set any placeholder it will not work.

Here is an example.

```
}
height={180}
>
props.onClick(imageIndex, tile.id)}
/>

```

**RectLoading** returns `` from **material-ui**

I also try to add some text but nothing to show.

```
Placeholder}
height={180}

.... other code
```

can you please look at this issue