Good output, stops too often

After testing this plugin for a while I decided to purchase the unlimited version. I need to import a blog with almost 4000 entries. Even using the extended version, most of the times the process is stopped with no error message after 20 entries. Every so often it is able to output some logging and import a few more at a time, but never more than 50 or 60. A week and a half ago I sent a support request but didn’t get any help dealing with this. It is a shame because the imported posts work wonderfully