I noticed some really strange/suicidal AI attack behaviour at least with Black creatures with Lifelink ability against Mirran Crusader at least.

AI attacked in different games with Marcov Patrician and Child of Night alone each time,(they weren't boosted by other cards so not to suffer lethal damage) against Mirran Crusader which has both protection from black and won't take any damage by them and also double strike =(first strike for AI if I remember well you said you have set it like this) so even without the protection AI's creatures couldn't have done any damage as they would receive lethal damage from first strike. So something is fishy here.