Hello Yan,
my bad. I see there was no category line at the beginning of the file you've just imported. You should now be able to find the entire flashcard list in the Uncategorized category in Organize Flashcards, so that if you create a new category folder, then select all cards in the Uncategorized category and move them to the category folder you've created, they should be stored properly.
I believe the difference between the files is that the one I uploaded contains both the definitions and the frequencies, whereas the others come with the frequency numbers only.
Hope this helps, you're welcome,
Shun