When I open my CSV file in Excel, the columns look fine.
I only have 2 rows: headers and one line of data.
But when I import and it asks me to:
Match the file columns with your subscriber list fields
The preview of the first few pieces of data in each column is clearly messed up. A few of the columns are pulling information from multiple columns...
I see you've already contacted support about this. We'll help you out there after we look at your specific file. Thanks!