Operating system: Windows 10
Graphics card: Intel HD Graphics 520 (built-in)
Broken: 2.80 RC 3
In the attached Blend file you will find one object named "Dead Object" because changing it from Edit Mode to Object Mode in any workspace causes it to switch from Object Mode to Edit mode in one of the other workspaces, so no matter how you try you can never get it out of Edit Mode.
I found I couldn't select one of my objects. I checked each workspace and found that the object was in Edit Mode in the Modeling workspace, so I tapped the Tab key to go to Object Mode (and of course I verified that the mode did change). Still couldn't select it, so I kept looking and found it had gone into Edit Mode in the UV Editing workspace. So I tabbed out there. Still couldn't select it, so I searched again and found it in Edit Mode once again in the Modeling workspace. It seems that whenever I change the Mode in one workspace, it toggles in another, as well, so I can never truly leave Edit Mode and never delete the object.
I tried deleting all its vertices to see if I could then get it out of Edit Mode, so that's why the Dead Object in the Blend file has no geometry.
I think this disaster occurred after using the Eye icons to hide and show Collections. I don't remember, so it's possible the object was in Edit Mode when I hid its containing collection.