Same problem here, it seems a bug that was introduced with one of the latest updates, maybe a week ago or something similar.
The functionality of this tool was perfect before.
The tool seems to search the keywords inside article/url/title/meta that have a perfect match with the one written in the focus field.
Title: Iphone, Android... which one?
Meta: Choosing from Iphone and Android is a....
In the focus field: iphone android --> gives 1 Yes (URL)
In the focus field: iphone, android --> gives 1 Yes (Title)
In the focus field: iphone --> gives 5 Yes
In the Preview Snippet the keywords are highlighted correctly...
This is a nonsense. Someone has a solution or a workaround?