Thxxx for the feedback ... but that is a very well known « bug », since the very beginning of the pre-order beta -- 5 weeks ago. It has happened far more than once, to many of us :
Sometimes, during a game, one or more of the A.I. demigods stop participating to their team's offensive drive and passively "loiter" in the back, at the life crystal. If they perceive a nearby attack, they usually respond ... but by then, their team is most often close to defeat.
I've lost many games because of that « bug » : 1 or 2 of my team8s were going AWOL, leaving me alone to shoulder the burden of the fight. I don't mind losing, but not because of a « broken feature ».
Since I've not played a lot of the recent updated build, I don't know if the problem has been reduced -- but it doesn't seem to be fixed, considering your report.
I do not recall having read any explanation from a SD or GPG representative concerning that state of affair : is it so difficult to fix ? Please point us to a pertinent thread if such an explanation has already been given.