Sort by title - new search

Hi,

we are implementing new search (https://microsoft-search.github.io/pnp-modern-search/). We have list of application and search only within this list. We would like to sort the results by Title (Name of application) but it is not possible because "Title" is not sortable. We have tried to map the "Title" on some "RefinableString" but this field is empty then in results and it is also not possible to filter by this.

Do you have any tip, how to fix it?

Thank you,

Mirek