dnd5e reactivity with race.advancement.byID

const selectHandler = async (option) => {
  race = await fromUuid(option);
  console.log(source); //<-- works
  console.log(adv);    //<-- undefined
  console.log(race.advancement.byId); //<-- works
}
$: source = race?.system?.source; 
$: adv = race?.advancement?.byId;