Well at-least can sometimes go hand in hand with this one. If you make the document tree large and then resize the window to a smaller size you can make the node|style|metrics|properties become unshown. Another one. If you open up a new inspector window and then resize the top display pane where it shows the document tree to a large size and then take the bottom corner and move it up so that its covering the node|style|metrics|properties bar. but can still see the bottom edge of the pane. Then Grab the pane and move it up as far as it can go. They end result is the document tree view and the node|style|metrics|Properties overlay. Attached a picture for it. Also sometimes when these happen you can get the scrolling of the window happening its really weird.
Created attachment 6571 [details] The Large Web Inspector
Created attachment 6572 [details] The Window Not Displaying the Lower Bar
Created attachment 6573 [details] When The Two Panes Overlay
Yeah confirmed, nice catches, p3 though, won't see this happening to soon.
This bug is no longer relevant since the landing of the new inspector in r23677