Connector wont execute on REST call

Hello, i'm currently developing a C# client where I need to instance some process via REST API. I have no problem executing any task with contracts, but when any userTask has a connector (specifically a rest connector to another server of mine), this won't execute and its skipped while the task is completed sending me a success response (Code: 204). However, if I perform the tasks on the portal every connector works perfectly.
The method i'm expecting to execute both the task and connector is {API/bpm/userTask/:taskId/execution} sending the correspondent json with the contract.

Is this a problem on my aproach or this feature is not included in the comunnity version 7.5.4?

Thank you in advance.