When attacking the Titan I lately have the feeling that sometimes the defense down applied by Athena is not being shown.
The symbol is not shown on the Titan, and when checking the Titan, it is not shown in the list of ailments either. From the amount of damage being done, I would say that it is active though.
I did not record the battles, but it happened at least twice.
I know, and I will try to record the next fights. Just wanted to leave it here because maybe someone else noticed the same and already has some footage.