Epoch / UNIX time is the number of seconds that has elapsed since 1/1/1970. Excel calculates dates by using the number of days that have elapsed since 1/1/1900. Therefore you are able to convert from one to the other by converting from seconds to days, and then adding on the 70 years difference.
The formula :- =(A1/86400)+25569 where A1 contains the UNIX time should convert to Excel date/time. Make sure you format the cell as the required date/time format, custom - dd/mm/yyyy hh:mm:ss
This field is being exported correctly so you will need to add a new column in Excel and use the formula above.