Hey, This one has me a bit baffled and I couldn't find any other threads with this specific failure I built this as a Windows Store, phone 8.1 XAML C# app with none of the debugging options, built the master version, tested on my phone, then built the packages. The certification failed on the "Supported API" test, with a huge list of lines like this one: This API is not supported for this application type - Api=AnchoredJoint2D_CUSTOM_INTERNAL_get_anchor. Module=unityenginedelegates.dll. File=UnityEngineProxy.dll. The Api part changes but the Module and File are all the same, The Api's go all the way from AnchoredJoint2D to WindZones So what is UnityEngineProxy and do I need it for the app to run?