Date-Time neutral fields
The template header indicates all kinds of information: whether a field is mandatory, what the field length is, and so on. Importantly, when there is a format requirement, the exact format is also listed in the header.
For DateTimeNeutral fields, note that the format that you see in Excel may differ from what is actually the cell value as shown in the following example:
Here, when you click the cell, its value is displayed in the formula bar on top (highlighted).
Make sure the value in the cell complies with the DateTimeNeutral format: YYYY-MM-DDTHH:MM:SS. You can type or copy the value in the formula bar. If the cell value does not comply, the import will fail.