Also having this problem, we have to revert back to an earlier version of the plugin (i believe we use 2.2.13 for this reason).
We need to be able to export the redirects prior to uploading.
Currently there is no way to revert back easily if imported redirects cause problems. In the past we could export all redirects as a back-up, import the new spreadsheet, and if it failed we could easily delete all the redirects and import the archived spreadsheet.