chrome extension content script cant get element by class

Look at screenshot:

enter image description here

  1. Iframe is minimized so you cant see any of its childs
  2. Target div displayed as child of iframe even we know fact 1.

Extension’s content script

console.log( targetDiv )   // output: undefined

Google Chrome console

console.log( targetDiv )   // output: targetDiv

How is that possible?
The other ‘normal’ elements are printed out in both cases.
Can you explain me this magic half-child element?

UPDATE: this div created dynamicly setInterval fixes problem!