Content properties not copied for draft when collaborative editing is turned off

When saving content properties for a new page, the properties are lost when saving the page. The contentId changes (for example from 1015852 to 1015854) but the properties are not copied to the new contentId.

This only happens when collaborative editing is turned off. With collaborative editing turned on, it works as expected.

We pass the AJS.params.contentId to a REST resource that implements:

    private final ContentPropertyService contentPropertyService;
    JsonContentProperty.ContentPropertyBuilder newValue = JsonContentProperty.builder()
            .value(new JsonString(json.toJson(pageConfiguration)));

Is there a better way to save content properties, or a workaround for this problem?