DynamoDB Update Snap doesn't appear to do anything

[Frijoles]

Hello, I've got a working DynamoDB creation snap working, but when I try to use the update snap, it doesn't seem to do anything. The snap itself turns green like it's happy, but nothing happens on the DB end. I've also replaced the table name with a bogus table and it's still happy. I've attached the settings of the snap. Checked my policy as well to verify I have update. I replaced all the values with things that should cause an error, but it's still green and not doing anything. Was hoping I'm not the first one to use it.

Attached a screenshot of the settings.

[Frijoles]

Following up, it looks like a mapper snap is required prior to this update snap in order to pass the Key value in. In the example above, I passed "test string" in the expression with $Key.login_id.S (my primary key) as the value to the Dynamo snap. That kicked it off.