ODK Collect fails to convert the data extracted from csv to dateTime format because initially there is no data that satisfies the format to be converted. My solution was to put a conditional in a calculate field that indicates that if ID is empty put a date that satisfies the format to be converted, otherwise extract the data from the csv file. Additionally to make the difference between dates use int((decimal-date-time(${study_date_format})-decimal-date-time(${current_date}))* 24*60). This solution, which I present in the attached file, makes ODK Collect and Enketo work in the same way. I hope this solution can help you sometime.
dateTime_receiver_test_functional_Enketo_and_ODKCollect.xlsx (13.5 KB)