Cloudsettings plugin doesn't work when uploaded to TestFlight

Hi, does anyone use key-value pairs storage with the ionic cloud settings plugin? I have an odd situation. The plugin works great when I am doing local builds. However, when I upload to the app store TestFlight environment it stops working with a “synchronize failed” error.
(also reported in the plugin’s GitHub repo)

(I am not using the native wrapper as I am on ionic-v1)