This thing just happened to me earlier today, but I was curious if you can go back and re-watch the replay of that attack on your base, and tell me if they rallied troops (while all are dead) to one of your resource buildings. I noticed at the end of the attack on my base, he/she rallied their troops to a resource building, but all his/her troops were dead/gone. I allso found out that you cannot use the rally if you have zero troops on the field.
Person who got me was Christoph, at the time ranked 47, Roman.