If you're importing Open Office / Libre Office Calc files or Excel spreadsheets into MySQL using PHPMyAdmin, you might have run into the occasional case where the process hangs with either a partially imported set or no records at all. After some messing around, I have found that this usually happens when there's a problem with the input data. In my case, this usually stemmed from duplicate primary keys or similar issues. Unique keys were detected fine.
In other words, PEBKAC.
P.S. I am currently using PMA v3.3.2.