attributes are removed before table is rendered

I've recently inherited a project and realized a column in our Datatables isn't being sorted properly. I thought this would be as simple as adding the HTML5 attribute data-sort to the <td> tag, but it seems any attributes (classes/ids/etc) are removed before they make it to the screen for our <td> tags.

Here we create a field and I attempt to add the data-sort attribute
thingFields.ts

class SeenBy extends allThings<MapRest.ThingsWithOtherthings> {
    readonly id = "seen-by";
    
    render(thing: MapRest.ThingsWithOtherthings): String {
        let popularity = thing.interfaces.reduce((acc, thing) => acc + thing, 0);
        return `<td class="seen-by" data-sort="${popularity}"> ${popularity} rating</td>`;
    }
}

When initializing the DataTable we do the following
thingTable.ts

private initializeDataTable(things: T[]): DataTables.Api {
    let columnDefs: DataTables.ColumnDefsSettings[] = this.thingFieldRegistry.fields.map((field, index) => this.generateColumnDefForField(field, index));

    let settings: {...} ={
        colReorder: true,
        data: things,
        columnDefs: columnDefs,
        drawCallback: () => this.refreshTable(),
        deferRemder: true,
        scrollY: this.height,
        scrollCollapse: true,
        scroller: true
    };

    let table = this.$table.DataTable(settings);
}

...

private generateColumnDefForField(field: thingField<T>, index: number): DataTables.ColumnDefsSettings {
    return {
        targets: [index],
        type: field.type,
        render: (data: any, type: string, thing: T, object: any) => field.render(thing),
    };
}

The resulting <td> entry for SeenBy is <td class="sorting_1">...</td> I'm not sure where the sorting_1 is coming from but as you can see, the class I specified and data-sorting is nowhere to be found.

This project is in a closed-off network so unfortunately I can't use the debugger or supply a link. I've spent most of my time investigating as to why, but maybe I should be adding this attribute after the table has been created. Either solution would be fine, but knowing why I've had this struggle would be great too.