Embedding a related action in a record list. Need help setting identifier in recordActionItem()

I'm trying to set up a record action to launch from a record list interface. It appears almost everything is working, but when I hit the button I get an error in the interface. The error message corresponds to a previous issue I had where the rule input (the record I want to modify) was null. Therefore I suspect it's not getting properly passed, and I called the identifier field wrong. What should I be using here?

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