Dates in exported contribution records are formatted "YYYY-MM-DD HH:MM:SS", but this formatting is not compatible with import formats which expect only dates and not times.
To recreate this:
1. Export a contribution row with a valid Received Date
2. Import the CSV file without changes, selected date format "YYYY-MM-DD" and matching the Received Date fields. An error occurs indicateding that the Received Date field is an incorrect format.
To fix the exported dates should be formatted as "YYYY-MM-DD" (i.e. without HH:MM:SS). The work around right now is to use Excel to reformat the date fields.