Sending Proform Webhook to Surecontact

I’m trying to send a Webhook to SureContact to add new subscribers. When I map the first name and email fields this goes through just fine. But when I try adding the checkbox field, my submission won’t go through. I’ve not gotten much information from the console except that the submission doesn’t go through. I tried add the “:implode” filter to my value and I’ve tried using radio buttons and I get the same result. Anyone have any thoughts about how I can get this to go through?