Response validation error: Does not have a value in the enumeration

I am getting this response validation error when I use 8.x-2.0-rc1:

{
    "property": "relationships.agency.data.type",
    "pointer": "\/relationships\/agency\/data\/type",
    "message": "Does not have a value in the enumeration [\"taxonomy_term--agency\"]",
    "constraint": "enum",
    "context": 1,
    "enum": [
      "taxonomy_term--agency"
    ]
},

It goes away if I manually unset the 'enum' from where it is, deep in the nested schema array. But I suspect that's not really fixing the problem. I'm happy to try some debugging if anyone has ideas.

If it helps, this site has a taxonomy vocabulary resource which is being overridden by this module from 'taxonomy_term--agency' to just 'agency'.