That's not good, it certainly sounds like a bug. Would you mind testing a few things.
First thing, we'd need to turn error reporting on. Follow the steps in the documentation to set gpdebug to true.
Then, to narrow things down, I think it would be best to edit some code. Open the file [YOUR_INSTALLATION]/include/admin/admin_menu.php and find the line that reads
echo '<input type="submit" name="aaa" value="'.$langmessage['continue'].'" class="menupost submit"/> ';
Change this line to read
echo '<input type="submit" name="aaa" value="'.$langmessage['continue'].'" class="submit"/> ';
Now when you go back to create a "New File", it will either work or display some error messages that will give us an idea of what is happening.
I'm sorry it's not working.
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