Datepicker writeValue is still updated in the datepicker, it is just handled a bit differently than in timepicker component.

We are already aware of some problems with the datepicker value updates in the latest MDB Angular version. It seems that there are some edge cases where this value is updated too early, which causes the input value not to be updated correctly. As a workaround please try to move the code to ngAfterViewInit hook or use Promise.resolve() to delay the update:

Promise.resolve().then(() => {
  // update value here
});