Unable to update Item Description based on EFF value when EFF is updated to blank

Summary:

I would like to create an item rule for item descriptions that updates based on changes to an EFF attribute. Specifically, if the "Keyword" attribute is updated to "green," I want "green" to appear in the item description. Additionally, if the "green" value is deleted from the "Keyword" attribute, I want it to be removed from the item description. I created a rule which updates the item description whenever the Keyword field is populated, but when I am having issues creating a rule that states that the Item Description should be updated if a Keyword field becomes blank.

Thanks!