Are you exporting to Excel or CSV? CSV has cleaner data.
You can open csv files in excel of course.
Sorry I have note seen this issue before.
OK so that will be something that Excel is doing to the field. It probably has it formatted as a currency field. It needs to be a text field.
Try changing column field type to text.
For a drop down field in BC the data would look like this for the choices: 2017,2018 with a comma between each choice
thanks, will check it out