How do you update the data in PropertiesService and show it in another Card?

The data always seems stale, or the card/UI is stale.

For example...

1. Set up a project for Google Calendar. Run the buildInitState function to initialize it

// appsscript.json
// set the trigger to build the home
....
....
 "addOns": {
    "calendar": {
      "homepageTrigger": {
        "enabled": true,
        "runFunction": "buildInitState"
      }
    },
    "common": {
      ....
....

2. Initialize function to build the home card

const userStore = PropertiesService.getUserProperties();

// setup userStore and add default values for date 
userStore.setProperties({
  date: (new Date()).getTime(),
});

const showSettingsPageAction =
  CardService.newAction().setFunctionName('showSettingsPage');

const handleDateChangeAction =
  CardService.newAction().setFunctionName('handleDateChange');

function handleDateChange(e) {
  //change the date to what user selects
  const newDate = (new Date(e.formInput.date_field.msSinceEpoch)).getTime();
  userStore.setProperty('date', newDate);
}

// Homepage card
function buildInitState(e) {
  const mainCard = CardService.newCardBuilder();

  // add a date picker
  const DatePicker = CardService.newDatePicker()
    .setTitle('set date')
    .setFieldName('date_field')
    .setValueInMsSinceEpoch((new Date()).getTime())
    .setOnChangeAction(
      CardService.newAction().setFunctionName('handleDateChangeAction')
    );

  // add a button to nav to another card
  const ButtonFindSlots = CardService.newTextButton()
    .setText('NAV TO SETTINGS CARD')
    .setOnClickAction(showSettingsPageAction);

  mainCard
  .addSection(DatePicker)
  .addSection(ButtonFindSlots)

  mainCard.build();
}

3. The showSettingsPage builds a new card.

function showSettingsPage() {
  const card = CardService.newCardBuilder();
  const cardSection = CardService.newCardSection();

  let content = userStore.getProperty('date');
  let p = CardService.newTextParagraph().setText(content);

  card.addSection(cardSection);
  return card.build();
}

Even when the user changes the date in the home card and navigates to the settings page, the date always shows the default date value.

I'm not sure if the data ins't updating or the card is not updating. I've tried to read the docs on action responses but I don't understand it's suppose to work.