When the object or array editors cannot evaluate an entry for any reason (syntax error, object undefined, etc.) then it will translate it into a string automatically verbatim. I believe the data is storing as a string because you are missing a single-quote after "b". So when that is evaluated, it fails because of a syntax error and then instead stores it as a string. Just add a single-quote after the "b" and it will be good to go.
But with that said, the # of records loaded is showing an incorrect number. However, the data is actually loaded as 2 records. So I will open a ticket to solve the incorrect number that shows after the data is loaded.