Custom mapping with typesenseType not available for sorting

[Draykee]

I discovered that a custom mapping defined with typesenseType like this:

updatedAt: {
    graphQlType: 'Int',
    typesenseType: 'int64', // use uint64, otherwise milliseconds wont fit
    valueFn: ({ variant }) => {
        return variant.product.updatedAt.valueOf() ?? new Date().valueOf(); 
    },
    outputFn: values => values?.[0] ?? 0,
},

Can't be used for sorting:

function sortableFields(): SortableField[] {
    return [
        {
            name: 'customMapping_updatedAt',
            alias: 'updatedAt',
        },
    ];
}

I was debugging the fields that are available while checking the schema and customMapping_updatedAt didn't appear in it.

If I remove the custom sorting and debug the documents getting created, I can see though that customMapping_updatedAt is used.
So I assume that The customMapping fields using typesenseType are somehow added after checking the sort schema.

My usecase: I want to sort products by "latest".

[toBeOfUse]

I couldn't get sortable fields working until I switched from the version recommended in the docs to Typesense version 0.24.0, which is the one that @michaelbromley said he uses