Here's a weird one: When I press Ctrl+J to join two objects (in Object Mode), nothing happens. However, if I then rotate the view a bit and press Ctrl+J again, Blender joins the objects for me. This happens all the time in my current project. This doesn't occur in a new project. Is there anything I should do to clean up my project or something? It's my first attempt, so I'm sure it's a bit messy internally. I can absolutely live with this oddity, but I just want to make sure I'm not about to break Blender or something.