timo
in Start and End time there should be ONLY the Time, without the date
example only 13:00
nothing more, i think you save also the day with the time in the app, but this has to be removed while exporting time only, as the date ist already in other colum.
https://www.exceltip.com/excel-date-time-formulas/entering-times-quickly.html
Excel stores dates and time as numbers and is used in calculation by the function. So it’s recommended to use dates as cell reference or using the TIME function instead of giving direct argument to the function. Check the validation of time values, or else the function returns #VALUE! Error.
Excel TIMEVALUE function only converts time values in text format to time values in number format.