Just as a point, in case anyone wants to bug report it,
You are only meant to be denied your sneak attack if you make the attack roll with disadvantage; that means that if you have 7 sources of disadvantage, and one source of advantage, and are thus making your attack roll as a flat roll, with neither disadvantage or advantage, then it is not supposed to interfere with your sneak attack - if you have an ally within 5 feet of the enemy, you would get your sneak attack just fine.
Larian have not implemented it this way - they have it set to knock out your sneak attack if you have any source of disadvantage at all, regardless of whether you're attacking at disadvantage or not, and it actually contradicts the toolitp which has the formal (correct) wording on it, last I checked.