Just upgraded to 2012, SP1.0: when I open my assy that has a toolbox part in it, the part does not show, its suppressed. When i try to unsuppress it says it cannot find. When I open it from the feature tree it opens in another window. Now I can unsuppress. Save it all, reopen the assy and it is suppressed again.
I tried opening a new assy, bringing in a toolbox item, twice. Closed and come back... its suppressed. Toolbox is not working for us, but I can still use the parts, so I thought.