Accessing store in another computer property using Options API

[3zzy]

If I follow this example from the doc: https://pinia.vuejs.org/cookbook/options-api.html

... and add a new computed prop that references an array from the store and returns a filtered view:

computed: {
    // note we are not passing an array, just one store after the other
    // each store will be accessible as its id + 'Store'
    ...mapStores(useCartStore, useUserStore),
    activeUsers() { return this.userStore.users.filter(u => u.isActive) }
  },

.. it doesn't seem to be reactive. Is this a known issue or am I doing it wrong?

Thanks