Categories are all `null`s

[lukehesluke]

Hi,

Every event in the feed (https://leisureworldmembership.leisurecloud.net/openactive/api/sessions) has field category which is an array of two nulls

An example (identifier: C3CLSIC20000118):

{
  "state": "updated",
  "kind": "session",
  "id": "C3CLSIC20000118",
  "modified": 2379563,
  "data": {
    "@context": "https://www.openactive.io/ns/oa.jsonld",
    "identifier": "C3CLSIC20000118",
    "activity": "Indoor Cycling Classes",
    "category": [
      null,
      null
    ],
    "name": "Keiser Cycling Speed & Pw",
    "description": [],
    "genderRestriction": "http://openactive.io/ns#None",
    "location": {
      "type": "Place",
      "url": "www.colchesterleisureworld.co.uk",
      "name": "Leisure World Colchester",
      "identifier": "LWC",
       // ...

[domfennell]

And also this issue if you/your team have a moment, @marcdriscoll @LeisureWorldColchester.