I had already commented on another topic but it's worth sharing it in here as it seems more informative.
Sneak attack simply doesn't trigger for me...
...As a software engineer myself I'd bet that it's a trivial issue, like that the event "leaving hidden status" triggers before the damage and thus doesn't trigger the additional sneak damage.
You are not the only one. I've never had it trigger. You'd think more people would have noticed this by now.
Edit: It isn't just leaving sneak. It does not trigger for any condition, including the prerequisite for another enemy of the target being within 1.5m
