I am having an issue with the style properties of my map. I imported the US Zip Code Tabulation Area map from a government website, and in a separate excel file I have a list of people connected to various zip codes. My original problem was QGIS was removing the leading zeros from my CSV file, which caused a lot of zip codes to appear blank. I created a .csvt file to declare the zip code column as a string, and this worked and allowed me to keep the leading zeros. However, now when I join this data to the zip code map, and then try to style based off of the 'name' category, the map disappears. I checked the attribute table, and all the names are correctly assigned to the various zip codes, but the map disappears anyway. The map previously worked before I added the .csvt file but obviously with the missing areas due to leading zero issues.
I am not sure why the map is disappearing after adding the .csvt file. I've included images to show how everything appears to be correct in the properties and attribute table, but the map just won't show up.
Here is the album where I show my process and the error.