Resolving Notion JSON String Issue for Client Project Linking

Hey, hoping someone can help me with an issue that's been driving me crazy Issue:

I need my agent to create a project in Notion and link it to a client by passing a relation field (Clients DB) with the client's Notion page ID.
However, the JSON that Lindy sends to Notion gets wrapped as a string, causing Notion to reject it.
The error I receive:

body.properties.Clients DB.relation should be an array, instead was `"{\"properties\":{\"Clients DB\":{\"relation\":[{\"id\"...`."

This suggests that the entire JSON block is being treated as a string instead of an object.