I created a SP mission in Tanoa where NATO troops would start in Kotomo? (The village on the north side of the Harcourt Bay) and march across the large bridge to attack Syndikat troops in Harcourt. The AI marched in single file across the bridge okay, but as soon as they went into combat mode and started fighting the enemy, the AI started to move towards the railings and, almost one by one, vault or "step over" the railings until they fell off into the water and died. They would constantly do the "step over" animation against the railing as they glitched through it, until they fell off. I cannot be sure if the AI not in my squad/group were doing the same thing, by every AI in my 12-man group did this.