mapping page is blank

Have you had a read through
https://wiki.smackcoders.com/WP_Ultimate_CSV_Importer_Free_Installation_and_Configuration

make sure you have a title for columns you want mapped i.e post_title
and it is in UTF-8

It looks like an odd issue. We have not faced issues in mapping section. Please check the below details in your CSV to fix the issue.
1) The uploaded CSV file should be formatted correctly with correct delimiter and escape delimiters.
2) CSV should be in UTF format.
3) Don’t leave the first column as empty in the CSV file.
Still you have the issue, please create support ticket in our helpdesk, our support team will fix your issue as soon as possible.