Slide Template seems broken

### Question

Is changing templates per Slide currently broken or did I get it wrong? Version: 6.0.2

### Background Info/Attempts

I've defined two master templates. One with page number and one without. For the introduction slide I want to switch to a simpler version.

Minimal Example:

```
const regularTemplate = ({ slideNumber, numberOfSlides }) => (





{slideNumber} / {numberOfSlides}


);

const introTemplate = () => (





);

const Presentation = () => (


Without Page Number


Default: With Page Number


);
```