My current case: When I alt-click an object inside a model in the viewport, then ctrl-click another object in that same model inside the explorer, any objects that I have previously interacted with/modified get selected.
This bug may occur via other methods of selecting children of models, or maybe even any objects in the explorer - but only when selecting multiple objects (ctrl-clicking)
This is not only for alt-clicking but various other stuff as well. Thanks for reporting this though! Really hope they fixed it. This issue has been annoying me for like 2 weeks now.