No clue what you did wrong, I was not there
You are describing the (typical)action from the Metadata Edit window?
Choose metadata from results, then it proceeds to the Cover.
You need to OK the Cover.
Configure Metadata (button at the bottom).
Your selected source may not have those fields enabled.
That window shows the Overall fields, enabled
BUT there is the
Configure Selected source, at the bottom, that allows a Per Source fine tune