In the midst of all this in 1350, there was a split within the Northern Court between Takauji and Tadayoshi ASHIKAGA (known as the Kanno Disturbance), which forced Sadahisa to fight against Tadaaki HATAKEYAMA of the Tadayoshi clan, temporarily making him join the forces of the Southern Court (after the end of the Kanno Disturbance he returned to the Northern Court).
1350年（観応元年）、そのような状況の中、北朝方は尊氏方と足利直義方とに分裂（観応の擾乱）、この間、直義方の畠山直顕とも戦わなければならず、一時南朝の軍門に下らざるを得ないほどであった（観応の擾乱終結後、北朝方に復帰）。