The trick is to use `str` inside the `contains`.

This query gives the expected result:

```
select ?item ?img
{
  hint:Query hint:maxParallel 400 .
  hint:Query hint:chunkSize  8000 .
  ?item wdt:P18 ?img . 
  filter contains(str(?img), "Montage")
}
```
[Try it][1]

Another way to achieve this is to set `hint:Query hint:regexMatchNonString true` and then use a normal regex.


(Huge thanks to Stanislav Kralin who found all this)


  [1]: https://w.wiki/7gq