vue buefy table sort nested array

I have a 2d array i’m displaying in a table using buefy, normally when I want to sort a column on render I can simply add default-sort=”field name” and it will sort for me. But because of the 2d nested array it doesn’t seem to work. Has anyone done this before? I’m trying to sort the table by the last column’s values.

<b-table
  :data="testArray"
  default-sort="quantity"
>
      <b-table-column label="Jan" v-slot="props">
        {{ props.row[1].quantity }}
      </b-table-column>
      .
      .
      .
      <b-table-column label="December" field="quantity" numeric v-slot="props">
        {{ props.row[11].quantity }}
      </b-table-column>
</b-table>

I have tried using just “quantity”, i have also tried using the whole “props.row[11].quantity” but that doesn’t also work.
The table itself renders just fine however,

enter image description here

My actual dataset goes like this:

[
    [{quantity=0},...,{quantity=0}],
    [{quantity=333},....,{quantity=717}],
    .
    .
    .
    [{quantity=0},...,{quantity=0}],
]

Its an array of arrays containing json objects, note the objects dont only contain quantity, they have other fields im omitting for clarity