Can't find problem causing a device crash but fine in simulation. Possibility related to settings data for datafield app.

I have a datafield app which stopped working after the garmin network was hacked. It completely crashed and refused to run.

https://apps.garmin.com/en-US/apps/e486c0c9-ba0c-4197-925b-a21bc65806f5

I've rebuilt it with the new sdk and uploaded it after testing on the simulator. The datafield runs fine on the device until I try to define a lat and lon value. When enter data in the settings for a latitude and longitude it crashes the app on my Vivoactive HR. It worked fine for months previously as I use it often. The simulator shows no problems with my test cases.

Any suggestions on how to debug this?

All I'm doing in the app is getting the settings:

wpnt_lat = Application.getApp().getProperty("lat");
wpnt_lon = Application.getApp().getProperty("lon");

And they are defined in the resources/properties.xml

<?xml version="1.0" encoding="UTF-8"?>
  <resources>
    <properties>
      <property id="lat" type="float">0</property>
      <property id="lon" type="float">0</property>
    </properties>

  <strings>
    <string id="lat_title">Latitude</string>
    <string id="lon_title">Longitude</string>
  </strings>

  <settings>
    <setting propertyKey="@Properties.lat" title="@Strings.lat_title">
      <settingConfig type="numeric" />
    </setting>

    <setting propertyKey="@Properties.lon" title="@Strings.lon_title">
      <settingConfig type="numeric" />
    </setting>
   </settings>
</resources>

Is this an old depreciated method?