Just downloaded ST 2.1 gpl. Release notes do not mention that this was fixed, and my test code indicates the same problem. What build has this patch?
edit: nuked my existing test data, regenerated it and changed the foreignkey/associationkey to null. What I've found now is that the first time I call the getter for the associated data, it returns null. The second time I call it, it works. This means if I'm accessing associated data in a DataView, I override prepareData to call the getter twice.