Deep Linking: resourceId not saved

[LaScha]

We're using deep linking to create assignments, and then want to access the line item created later for assignments/grading service.

We put the resource like this:

resources = [
            {
                "type": "ltiResourceLink",
                "title": "Test Title",
                "url": "https://www.our_url.com",
                "lineItem": {
                    "scoreMaximum": 100,
                    "resourceId": "our-resource-id",
                    "label": "Test Title",
                },
                "custom": {}
            }
]

The deep linking appears to work fine, and the assignment is successfully created. However, later, when querying for line items with a POST request to the line items url, there are no resource ids to be found! There is a line item with this particular assignment, but there is no resource id to be found. All I see is:

{'scoreMaximum': 100.0,
  'resourceLinkId': 'some-random-string',
  'id': 'the-line-item-url',
  'label': 'Another title'
}

 It looks like it's programmatically creating one for the assignment (with its own title based on the assignment title,  not matching this line item) . What am I missing? How can I make sure the resource id is later attached so we can query for adding grades?