When Excel opens a spreadsheet, it does some automatic formatting of the cells within the sheet. If a cell appears to contain a date, Excel converts the cell to a date. Most of the SOC codes with the prefix "11-" look like dates in the month of November to Excel, so it converts the cells to dates.

This occurs when using CSV Exports, and can be avoided by using Excel exports:

This article explains how to use Excel to manually open a CSV downloaded from Analyst such that Excel will not convert "11-" SOCs to dates.