If you are redirected to blank page after clicking Import in Step 5, and only part of the products from your feed are imported, the import has been interrupted by a timeout. Anytime you run the import in the admin user interface, the import will be subject to the php limitations of OpenCart and your server. This usually results in a timeout if you are importing a large amount of products from your feed, such as 10k products or more.
We have 2 solutions to get around timeouts:
1. Run a partial import. In step 5, under Items to Import, set a range of products to import: http://hostjars.zendesk.com/entries/22032291-Step-5-Import. For example, set the product range from 1-5000 products for the first import, then 5000-10000 for the next import. You can adjust the amount of products in import range to meet the server's limitations without timing out.
2. Run the import in a cron job using a presaved settings profile: http://hostjars.zendesk.com/entries/21760081-Importing-from-cron-task. Imports run by cron job are not subject to your server's php limitations.