I'm having the exact same issue with Cp5.5, as reported here in a few threads.
The Zoom area "Source" as defined is not what is displayed in the display.
See this sequence of images:
Image may be NSFW.
Clik here to view.
in edit mode - want to zoom definition on left side
Image may be NSFW.
Clik here to view.
playback - as zoom begins, content is NOT the definition
Image may be NSFW.
Clik here to view.
zoom is complete: not correct.
I've opened and closed Cp, will do a restart next --
thanks for any help,
christine