'Object is not iterable' when setting a custom field (object) on Object Type through API

[Leon-Pay]

Deployment Type

Self-hosted

NetBox Version

v4.0.2

Python Version

3.11

Steps to Reproduce

Create a virtual machine

Create a custom field for "Virtualization > Virtual Machine" with type Object (Journal Entry)

Create a Journal Entry, ex. on the demo vm1 (361)

Set the custom field to the Journal Entry with the API, it works with the GUI

ex.

curl -X 'PUT' \
  'https://demo.netbox.dev/api/virtualization/virtual-machines/361/' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'X-CSRFTOKEN: xxxx' \
  -d '{"custom_fields": {"api_test_custom_field_object": "1"}}'

Expected Behavior

Get repsonse 200, set the journal entry to the custom field

Observed Behavior

Cant add the entry through the api

{
  "error": "argument of type 'JournalEntry' is not iterable",
  "exception": "TypeError",
  "netbox_version": "4.0.2",
  "python_version": "3.10.14"
}