Why is filterFn being completely ignored?

[HynekS]

I was assigned to fix a bug in a rather complex table. The issue is that filtering (and sorting) is not working on fields with non-string values. In this specific example, the value is an array of ids that gets mapped to a comma-separated string of localized names. The filtering is done via a simple text input (it would be better to use a multiselect, but the issue still stands).

I know I can use a custom filterFn (and I have used it successfully on a side project before). But when I tried to use it here, I ran into a weird issue: the filterFn does not seem to run at all (no alerts or console.logs if I'm updating the filter).

const tableSchema: TableSchema<PostListTable> = [
    {
      accessorKey: `tags`,
      header: `Tags`,
      accessorFn: (row) => {
        const tagData = row.tags.map((tag) =>
          row.tagDetails.find((tagDetail: PostTag) => tagDetail.id === tag)
        );
        return tagData.map((tag) => getLocalizedValue(tag?.name)).join(', ');
      },
      filterFn: (row, columnId, value) => {
        alert("Hello?") // <-- never runs?
        return true;
      },
    },
  ];

The code is using the onColumnFiltersChange method in a manner that is a little confusing and suspect. I guess the filtering is happening here, because if I comment onColumnFiltersChange out, all filtering ceases to work.

const onColumnFiltersChange = (
        updater: Updater<ColumnFiltersState>
      ) => {
        props.onColumnFiltersChange(
          updater instanceof Function
            ? updater(table.getState().columnFilters)
            : updater
        );
      };

I don't fully understand what the updater is doing here and whether (and how) I should pass getFilterFn() here. I found this reply, but it is even more confusing. Or is the issue somewhere else?

[HynekS]

Closing – as it turns out, the filtering was handled completely by back-end (and the data were being refetched), so it was not an issue with the table itself.