Since we were converting the field to lowercase we ended up inserting meta in all lowercase, regardless of what it was in the CSV file. We should only be using the normalized field name when looking at the default columns, and should instead rely on a case-insensitive regex for the special columns.
One thing to note is that we're still defaulting the $headers array to the normalized field, as we don't want to change what is being passed to the filter for unmapped columns.
Christopher Allford