KAFKA Connect, $lastCheck field does nothing


I have the kafka connect source running with the following properties

the query is:

MATCH (n:Note) WHERE n.createdAt > $lastCheck RETURN id(n) as id, n.id AS nid, n.createdAt AS createdAt

This never publishes data to my topic. If I change the CYPHER to remove the $lastCheck, something like:

MATCH (n:Note) RETURN n.id as nid, n.createdAt as createdAt

it works fine.

Does anyone have experience getting the kafka connect source query to work using $lastCheck? I can't poll my data otherwise making this whole thing totally useless.