Answer
We had set an idle timeout by default which set the status of an individual to "Away" when the timeout was reached.
We have added a large number of new features and changed the settings so they no longer default to an idle timeout although this can be set in preferences.
These changes were part of GMS Instant Messenger V2 which was part of build 3136 and so this is no longer an issue in builds 3136 and later.
See Also:
Keywords:IM messenger presence away instant