I have built a custom connector for the Xero API using Postman and after connecting I can make requests. The issue is that some requests require headers or body content, which is fine to do in the connector builder by hardcoding the values in the parameter tab. However, in Studio I am unable to set the values for these parameters and so I can only make requests that don’t require any custom parameters. Even leaving the values hardcoded in the connector builder doesn’t work when making the call from Studio.
I hope you are trying to use http request to send the requests…in the properties you will see option called parameters which can be given and used in your body …those parameters can be linked to variables in your flow
Please check the configuration part in this doc to know about parameters in body
If ypu can send the flow screenshots that would help understand your issue