This is a functional bug. When a templar moves adjacent to another templar, where the "turn" button would overlap it's neighboring unit, the templar cannot be turned. Attempting to press the button simply selects the templar instead of spending the AP to rotate the templar.
I am using the Samsung Galaxy S3 with Kitkat, but I expect this would be true for any platform. I also cannot believe that I haven't seen this anywhere in an FAQ, the manual, noobie questions, or anywhere else. I can't be the only person facing this issue, can I?
ajbloomie - I have moved the thread to bugs for you. Welcome to the forum!
The easiest solution is to tap an additional square out to the right (if you are turning right). You'll hit the same issue if there is an alien on your flank. You can tap any square in that "line" and you'll turn.