Content Comparison

Although you cannot select insights custom fields from the field picker, it is still possible to edit them using the advanced section.

Step-by-step guide

1. Select the edit issue action 
2. In the advanced block add the following, substituting the name of the field for the name of your field

{
  "fields": {
    "My Reference Object (Multi Select)": [
      { "key": "TEST-17" }
    ],
    "My Reference Object (Single Select)": [
      { "key": "TEST-18" }
    ]
  }
}