Web Messaging guest attributes not persisting on widget init

Trying to set custom guest attributes for authenticated users when initializing the Genesys Web Messaging widget. Passing the JSON payload to the init method, but the attributes show up as null in the transcript. The docs say to use the guest object with customAttributes.

Here is the I’m using. It doesn’t throw an error, just ignores the data. Am I missing a step in the flow? The userId works fine, but the custom keys are gone.