Error using Drupal Feeds to upload a comment in a text field
I was running into this same issue myself where half of my records were getting cut off when I uploaded them via the Feeds Importer. I found an answer that was posted on a Drupal forum that indicates that the problem is not with Feeds, but with the file itself.

It appears that by default Excel exports your CSV file into ANSI format, which creates issues when there are dates embedded within one of your fields.  By using Notepad++ and converting the file into UTF-8 it works. Here is the link which gives more details. 

https://www.drupal.org/node/2502761

NOTE: It also appears that if the file is encoded in UTF-8 BOM, then the CSV file can still be read by Drupal and Excel. Otherwise Excel treats it as a fixed length record.