Argent, I think it's an artifact of the book being split. It was planned to be the final book, but now book 5 will be the final book. This book was not as satisfying as previous books because there wasn't really a meaningful climax or ending. Kip doesn't figure out what he's missing about the situation, and then we see the big enemy gathering at the end just as a hook for the next book.
Sometimes splitting works well, and sometimes it doesn't. This doesn't affect my enjoyment of the rest of the book, but it feels like I can't recommend it quite as wholeheartedly as usual until the final book is available.