i know that but ower 40 turns...that was putting me in a dilemma
Almost certainly a case of Occam's Razor, with the explanation being your Mortu was lazy and didn't want to kill anything. :)
Being serious, I've seen my Mortu unlock Peril 4/4 in a fight, also seen him miss 10 chances in a row. At 20% it's just gonna end up with a pretty wide range of results from fight to fight. I wouldn't put too much stock in it.