I upgraded to 10.2.1 last week and all my projects (using both Swift and Objective-C) now never update the Variables view on hitting breakpoints or if the code crashes. The activity wheel just spins forever (well, certainly longer than my patience). Variables can be inspected by using print in the output pane, immediately.
I've uninstalled and re-installed Xcode, cleaned projects, checked everything I can think of. Has anyone else hit this and resolved it?
I'm not able to replicate your issue - what happens if you create a new project, set breakpoints etc. and do a run thru...?