Importing CSV - Unable to add to existing columns?

I’m trying to import a ton of tasks to an existing board. I’m using the CSV import technique, but when I list the column name in the “Section/Column” area, it creates a new column with the name identical to an existing column instead of adding them to the existing column. The casing, spacing, and everything is identical. Has anyone run into this and found a solution?

@Ashley_Norman this unfortunately is expected behavior today. You can upvote this suggested change HERE: CSV Import to existing Sections