Some lists exported from Attendease are in .csv format. Excel doesn't handle this file type properly so, in order to make sure you preserve all extended characters, you need to convert it into a .xlsx file yourself. To do this, upload the Attendease .csv file into Google Spreadsheets and then export the file to .xlsx. You should then be able to open the file in Excel. We are working to offer .xlsx downloads instead of .csv and will be rolling those out over the next few weeks.