Flanking strikes (Thief trait)
That’s how it should work, but… yeah sometimes Anet doesn’t follow its own rules. Had the same types of problems in GW1, ex. a skill says it affects “other allies” but also affects the user. It’s a glitch, who knows if they’ll bother to fix it.
it will take a while until anet will do this.. with all this huge engangement in living story pve they always miss some details