Mixed data types in API export

Hi All, 

I have a survey which uses a csv file to populate embedded values used in a series of drilldown questions. The survey responses are extracted via a python script with “useLabels : True” set in the download request. 

Recently the survey was updated to add a new response option. Since that change, the API extract populates several columns with both answer text (STR) and recode values (INT). So I get text values and numerical values--which likely correspond to the csv file which populates the answer option. 

Is there a reason why our other surveys using the same structure (but have not changed) continue to export text labels without any problem, while the recently changed survey has mixed data types in some columns?

Many thanks for your thoughts.