My first guess is that it's early in your summer so waiting another month will reveal if it's the tuber at fault or the old stand-by of "genetics", which do change. I can't speak of stunting but it wouldn't shock me if it were possible.
I've had Akita many times and it's never been a huge producer of blooms like some others have been. The same is true with the popular, Vancouver, yet I wouldn't want to be without either one.
