There is a difference in how this works from 2010 and 2011.
In 2010 when the Workset is first made there is a check box to make that Workset “Visible by default in all views”. If this box was not checked when the Workset was made then that Workset will not be visible by default in any new views made in the project, and you will have to change this visbility setting in the VV of each view. To fix this you will have to make a new Workset, check the “Visible by default in all views” box, and then move everything in the model from one Workset to this new Workset. See top image on the side.
This issue was addressed in 2011. If you look at the Worksets dialogue in 2011 there is an additional column for “Visible in all views”. Worksets with this box checked will be viewable in new views (such as sections). See bottom image on the side.
Thanks to my fellow Technical peeps for this info. on Worksets.