Error 500 when sending item mutation with column_values

Hello,

Not sure what I’m doing wrong here. I see no red lines in the API Playground when sending this mutation but I’m getting a 500 response every time.

mutation { create_item (board_id: 2782361481, group_id: "new_group", item_name: "Test", column_values: {text7 : "test-data"} ) { id }}

Results in:
{
  "error_message": "Internal server error",
  "status_code": 500
}

This query successfully adds a new item when I exclude the column_values. Any idea what I’m doing wrong?