Automation stopped working to copy text into long text field

Today an an automation that has been working for more than a year stopped working due to an error relating to a long text field in Monday. I’ve checked the data, removed spaces, ran it again - still the same. Any pointers/suggestions? The automation is creating an item on a Monday board. Error is:

The operation failed with an error. [200] invalid value, please check our API documentation for the correct data structure for this column. Guide to Changing Column Values [ Error Code: ColumnValueException / Error Details: {“column_value”:“{"text"=>["Organisation name, street address, city, postcode, UK"]}”,“column_type”:“LongTextColumn”} ]