This question was already asked and answered for Titanfall 1, but I wonder if there are any differences for Titanfall 2.
I just had this situation where I (in Ronin) meleed another Titan who was doomed at least three times. We were hitting each other and then I was doomed to and he performed an execution on me, which was very frustrating.
(My Sword Core was NOT activated at that moment.)
I felt like this was happening before, so I wanted to ask:
Is there more to Titan executions than meleeing a doomed Titan?
Best Answer
For starters, I have seen this behavior before too and have not found an easily reproducible scenario for it. 9 times out of 10 the execution works as expected.
There are several points to make, although a recording would have really helped to get to the exact reason for the execution not to happen.
The other linked question states that "you cannot trigger an execution from behind" which is false in Titanfall 2.
If another titan is doomed but is ejecting (or going nuclear) they cannot be executed, although this doesn't sound like what you described.
If a titan is doomed, but has picked up battery and has a shield, the shield will prevent that titan from being executed.
It is possible to stun lock another titan with melee when the other titan is moving forward, if due to timing the other titan punches just prior to you punching, then you will be hit back, miss your punch, and then move into another punch. If you are hit into a wall and knocked back into the second punch, this is essentially a stun lock.
There is also a slightly buggy issue with titan executions. If you are on something and the other titan is below you, for instance if you happen to be standing on a car while the other titan is not, it is possible that the execution does not trigger for some reason. It is also the same if you happen to have the high ground during the melee encounter. I am not sure if this is a visual bug where the attack visually takes place but does not actually register as a hit towards damage, or what, but I have observed this in several instances. It is certainly not consistent though.