How custom lists are stored
Once you create a custom list, it is added to your computer's registry, so it is available for use in other workbooks. If you use a custom list when sorting data, it is also saved with the workbook, so that it can be used on other computers, including servers where your workbook might be published to Excel Services and you want to rely on the custom list for a sort.
However, if you open the workbook on another computer or server, you do not see the custom list that is stored in the workbook file in the Custom Lists dialog box that is available from Excel Options, only from the Order column of the Sort dialog box. The custom list that is stored in the workbook file is also not immediately available for the Fill command.
If you want, you can add the custom list that is stored in the workbook file to the registry of the other computer or server and make it available from the Custom Lists dialog box in Excel Options. From the Sort dialog box, under the Order column, select Custom Lists to display the Custom Lists dialog box, select the custom list, and then click Add.