Note that the unselected frame is still iconified and lacks a toolbar.
Switching to that frame using Xmonad bindings would deiconify it.

7. C-x 5 o
   [Nothing changes.]

8. (select-frame (next-frame)) C-x C-e C-m
   [Nothing changes.]

9. (select-frame-set-input-focus (next-frame)) C-x C-e