I an existing project to 1.3.1. The app uses a toolbar, showing icons (accept, discard, etc.). On Droid, the icons are still there. On iOS, they're all missing. I can click (in the simulator) where I know they should, and the handlers work as expected. But the images aren't there.
When I look in the debug folder (C:\BikeApp\FrontPack\FrontPack.iOS\bin\iPhoneSimulator\Debug\FrontPackiOS.app), which I presume is used as the app is sent to the simulator, I see that the .PNGs, but they all have size of 0 bytes.
Here is some (maybe) relevant build output. Any help is greatly appreciated as this prevents me from going further to deployment 
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4>Target "_CollectBundleResources" in file "C:\Program Files (x86)\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets" from project "C:\BikeApp\FrontPack\FrontPack.iOS\FrontPack.iOS.csproj" (target "Build" depends on it):
4>Task "CollectBundleResourcesTask"
4> Copying Resources/account.png...
4> Copying Resources/contact.png...
4> Copying Resources/Default-568h@2x.png...
4> Copying Resources/Default-Portrait@2x.png...
4> Copying Resources/Default-Portrait.png...
4> Copying Resources/filter@2x.png...
4> Copying Resources/filter.png...
.
.
.
4>Done executing task "CollectBundleResourcesTask".
4>Done building target "_CollectBundleResources" in project "FrontPack.iOS.csproj".
4>Target "_CollectBundleResources" skipped. Previously built successfully.
4>Target "_CollectPngImages" in file "C:\Program Files (x86)\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets" from project "C:\BikeApp\FrontPack\FrontPack.iOS\FrontPack.iOS.csproj" (target "_OptimizePngImages" depends on it):
4>Done building target "_CollectPngImages" in project "FrontPack.iOS.csproj".
4>Target "_CollectPngImages" skipped. Previously built successfully.
4>Target "_DetectSdkLocations" skipped. Previously built successfully.
4>Target "_CoreOptimizePngImages" in file "C:\Program Files (x86)\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets" from project "C:\BikeApp\FrontPack\FrontPack.iOS\FrontPack.iOS.csproj" (target "_OptimizePngImages" depends on it):
4>Building target "_CoreOptimizePngImages" completely.
4>Output file "obj\iPhoneSimulator\Debug\account.png" does not exist.
4>Using "OptimizeImageTask" task from assembly "C:\Program Files (x86)\MSBuild\Xamarin\iOS\Xamarin.iOS.Tasks.dll".
4>Task "OptimizeImageTask"
4> Executing task: Xamarin.iOS.Tasks.OptimizeImageTask
4> Tool /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/pngcrush execution started with arguments: -q -iphone -f 0 Resources/account.png obj/iPhoneSimulator/Debug/account.png
4> Tool /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/pngcrush execution finished.
4>Done executing task "OptimizeImageTask".
4>Done building target "_CoreOptimizePngImages" in project "FrontPack.iOS.csproj".
4>Target "_CoreOptimizePngImages" in file "C:\Program Files (x86)\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets" from project "C:\BikeApp\FrontPack\FrontPack.iOS\FrontPack.iOS.csproj" (target "_OptimizePngImages" depends on it):
4>Building target "_CoreOptimizePngImages" completely.
4>Output file "obj\iPhoneSimulator\Debug\contact.png" does not exist.