Missing Column after Connecting to a CSV File

Issue

After connecting to a comma separated values (CSV) file, you may notice that a column (i.e., a dimension) from the underlying data is missing.

Environment

Tableau Desktop
CSV File

Resolution

If possible, migrate your data from the CSV file to a more robust data source, such as a relational database. Connecting to a Microsoft Excel file will also correct this issue. Excel will handle duplicate column names by slightly modifying the duplicated column name so that they are all unique.
Otherwise, create a schema.ini file that will explicitly declare each column header contained in the CSV file. Ensure that this schema.ini file is located in the same folder as the data source. For more information about schema.ini files, refer to the Displaying Data Types Correctly article.

Cause

One possible cause for this issue is that the missing column has the same name as another column in the data source. The omission of the column is caused by a limitation within the Microsoft JET Database Engine and the rules it uses to retrieve records from text-based files.

Additional Information

Note: Jet-based limitations can only occur in workbooks created in Tableau Desktop 8.1 and earlier that use Excel and text file data sources, and workbooks that use the legacy connection and Microsoft Access data sources. To avoid Jet-based issues, consider upgrading your Excel and text file data sources. For more information, see Upgrading Data Sources in Desktop Help.