Application.Properties have stopped functioning

I was using Application.Properties() to allow users to enter waypoints (within an Array) with at least some comfort (as the existing waypoints don't provide their details over API).

It was already working - but suddenly no longer.

Connect IQ tells me, that this setting can't be "updated" (?) - I should try it again.

The Simulator allows me to add data - I can even edit it; I'm also able to access it in my app.

But when I close the Simulator's App Settings Window and try to edit a waypoint again, I get "

Sorry, this page is currently unavailable.

Please try again later.
"

Any ideas anyone?

SDK 8.2.3

API-Level 3.4.0

<settings>
    <setting propertyKey="@Properties.waypoints" title="Waypoints" maxLength="10">
    <setting title="Name" type="string">
        <settingConfig id="name" type="alphaNumeric" required="true" maxLength="25"/>
    </setting>
    <setting title="Latitude" type="string">
        <settingConfig id="lat" type="alphaNumeric" required="true" maxLength="16"/>
    </setting>
    <setting title="Longitude" type="string">
        <settingConfig id="lon" type="alphaNumeric" required="true" maxLength="16"/>
    </setting>
    <setting title="Active" type="boolean">
        <settingConfig id="active" type="boolean"/>
    </setting>
    </setting>
</settings>