TitleContainer does not exist in the current context error

While attempting to resolve the last issue I posted (see iOS - Load XML content file using TitleContainer.OpenStream), I did a rebuild on my project and now I’m getting the error “TitleContainer does not exist in the current context” in a number of places - AudioEngine, SoundBank, WaveBank and ContentManager.

I have gone into the AudioEngine code and tried replacing “TitleContainer” with a fully qualified name, but when I type “Microsoft.Xna.Framework”, TitleContainer does not appear in the list of available methods and classes etc.

This happens in both the last and latest versions of Xamarin studio. I am using Monogame 3.2 latest release, and I have verified that the static class TitleContainer exists in the correct namespace. Apart form the qualified name to test the AudioEngine, I have not changed the monogame code at all.

Can someone advise what has broken please? Thanks.