I was trying to split the pipe delimited string column which had a column name {Bill Code} in Derived column transformation followed by Flatten transformation, Derived transformation which will split the string and convert it into an array and Flatten will convert them into individual rows.
Ex: B12|B13|B14 to ["B12", "B13", "B14"]
Then I passed this column with {Bill Code} name to flatten transformation and went to data preview it threw an error "Unroll value {Bill Code} must be an array", although the bill code column was an array but it was not honoring it, then I had to change the column name from bill code to code and then the flatten transformation honored the column as an array.
Conclusion : Flatten transformation is not honoring the array column name with multiple words separated by space and enclosed by curly brackets .
