Setting of Type "Dates" - Works for WF but not preserved in the Phone App

I have a date setting that works fine as a setting and the watchface reads this and behaves as expected 

In Connect IQ on my Phone (iOS) it shows a date picker dialog.

When I save this in ConnectIQ app on my phone "Settings Succesfully Saved" 

However if  I  hit the settings button again - the date is blank in the settings dialog and when I tap on the date field it defaults to today (regardless of what I just set as a date)

  Why is this existing setting value not preserved in the Phone Connect IQ Setting dialog ?

I have seen some apps use date in text format   DD-MM-YYYY rather than "Date"  - is this why ?

Thanks

Settings Code : 

<setting propertyKey="@Properties.OverRideStreakDate" title="@Strings.OverRideStreakDate">
<settingConfig type="date"></settingConfig>
</setting>