both I and my brother have seen this in both twisted treeline and summoners rift. in some customs, we noticed that soraka bot would very often just stop moving, attacking, doing anything. she would just stand there in the midst of whatever was there, unmoving. sometimes, after a while, she would walk back to base and sit there for a bit like a DC'd player. no clue whats going on with this.
I also noticed that too whenever I messed around in custom games on Summoners Rift. I'd set the Soraka bot to Intermediate (I usually play 3v5 when testing how to play a champion) and it always seemed she was dying while I wasn't paying much attention. When I got into lane with her, I noticed she'd just stand there for a bit, doing nothing. Sometimes when she was low on HP and the enemy bots were chasing, she would completely stop moving and be killed off (so that explained why intermediate Soraka kept dying off to BEGINNER BOTS).
I'm assuming when she's low and running away from the enemy, her AI hasn't updated yet and is still trying to heal herself from her old kit. As for when she stands completely still with full HP or walks back to base and does nothing, I'm not sure about that. I assume that in the case that she stands still with full HP in lane with someone who has low mana, she's trying to use her old E on you, but I'm not entirely sure about that.
