defaultFieldValues causing fields to not show on modal window

[AdtrakChrisRutter]

Hello.
I'm trying to add an action to create a new invoice.
The payload currently looks like this.
{ "entityApiName" : "Invoice__c", "defaultFieldValues" : { "Service_Agreement__c":"⌗parentrecordId⌗", "Account__c":"Service_Agreement__r.Account" } }

When we click on the "New" button, the invoice modal is launched, but the Service Agreement and Account fields are missing from the modal view.
If we remove the defaultFieldValues from this Payload, they reappear.

Any idea what I've done wrong?