I just ran into a problem where this behaviour caused the death of my Paragon despite being 100% preventable (I think this is the most I've been frustrated at the AI since I started playing).
I just watched as a Brilliant destroyed my Paragon from full health by this weird behavior where my Paragon would drop the shields to vent flux at ~20% or so (I was 100% health and armor at this point), during this time the Brilliant took the opportunity to fire off their plasma canon while my Paragon AI just sat there thinking about putting up the shields (at near zero flux at this point), finally decides to turn them on; shield slowly wraps around the Paragon (still taking more damage from the Plasma), looking good..and then vents at something like 10% flux, takes more plasma damage thinks about putting up the shields again, finally does, and it repeats in this pattern until death.
At this point in the battle I was isolated, so only needed to deal with the one Brilliant, which kept itself behind me with it's superior mobility. This isn't really too much of a problem since the medium mounts on my Paragon are filled with Phase Lances, so I should of been fine if the shields were kept up (even if it was just to wait for more help).
I thought it might take the armor and hull into account with this dangerous behaviour, but it didn't let up until it was destroyed. I've sent the save, though not being able to generate the exact conditions to cause the behaviour probably isn't all that helpful, but if I can find something more solid, I'll update.