Blight cannot be finished because of a monster which spawned inside a settlers ore textures

Monster spawned inside settlers blood ore and it cannot be killed, it is last monster so blight neither can be completed nor failed... with blight atlas tree and ~1div of scarabs it is very unpleasant experience.

Reference number is 1,257,957,535

There are 2 monsters actually, adding screenshot with the 2nd one, in case if minion type might be important detail.