Scenario: I've just connected to a stream, and created a new repository workspace. I loaded the 2 components of it, and modified some code. If i open the Pending Changes view, i can't see any pending changes there (and my "show full view" is selected, so I should be seeing both the incoming, outgoing and suspended change sets).
My files are saved and i can obviously see the changes in the files, but no pending changes appear in the pending changes view.
For your changes to be displayed in the "Pending Change Views", you need to:
(I tend to prefer the second method, because it allows me to chose what part of the -- potentially huge -- sandbox I need to refresh)