On May 11th, Movable Type 5.02 was released and contains fixes for a number of issues including one security vulnerability. They highly recommend for users to upgrade MT. So, I did. And I used this opportunity to some updates, too.
This time, I have no trouble even about ImageMagick.
After that, I feel some quicker about MT response. And suddenly, Crypt-DSA becomes working well on MT. Why?