titleCase fails to transform name

I have a line of code in an hbs helper:

<WindowHeader onClose={onClose} title='{{titleCase name}}' />

When I run a plop command and name is set to someName, all of the kebab and pascal casing conversions work fine, but the titleCase one does nothing.

The output is:

<WindowHeader onClose={onClose} title='someName' />

Am I missing something or doing something wrong? The handlebars braces are being read just fine as it's replacing the template with the value, it's just not converting the value to title case