For other users : I’ve solved this! The query doesn’t automatically extend the number of columns it can refer to if you add questions, so if your survey started with 10 questions, the number of columns in your query will remain as 10.
You need to go into the source step of your query, then find the code reference to ‘Columns = X’, and whatever number X is, replace it with the correct number so that the query registers all columns in the dataset.
