Creating Document with REST API sets field always to None in one specific DocType

Hi there,

I am currently developing a mobile app based on Frappe. Everything works well with the REST API: Creating Documents, Updating them, etc.

However, when I want to create a Leave Application, I just cannot set the field “leave_approver”. When I create a POST request with all necessary fields incl. “leave_approver”, all fields are set to the correct value, but “leave_approver” is None.

With other documents all works well. Also creating the “Leave Application” in the Frappe console works. etc.

So: Why is there one specific fields in one specific DocType where the field cannot be set?

Thank you so much!