From the API playground:
mutation{change_multiple_column_values(board_id:654, item_id:456,
column_values: "{
\\"notes\\" : \\"y\\",
\\"effort\\":\\"3\\",
\\"dependent_on\\":{\\"item_ids\\": [123,345]}
}"){id}}
returns error: SyntaxError: Unexpected token < in JSON at position 0
same syntax, changing “dependent_on” column to a “connect_boards” column with appropriate change in item id, works correctly
Any ideas?