[SOLVED in version 15.2] We are aware that the counterattack skill is still not working as intended in the game. 

This also affects the rare fire-element titan 'Ancient Tiger' because its Special Skill 'Sable Slasher' contains a counterattack. For further discussion on this bug, please go to our Forum (https://forum.smallgiantgames.com/t/known-issue-15-1-wrong-side-counterattack/51018 and https://forum.smallgiantgames.com/t/known-issue-15-1-red-rare-titan-hit-bug/50940)