After running the import when accessing the import set table gives an error 'An invalid XML character (Unicode: 0x3) was found in the element content of the document.'
When the data imported from a file the additional columns are created based on the columns present in the file. If the data present in the file is with incorrect data then columns created contain invalid characters that make the whole table becomes unreadable.
To resolve, delete the invalid columns which will restore the table back to normal. Address the incorrect data in the file and import it again.