Ambush Scarab of Potency bug

When using Ambush Scarab of Potency and opening strongboxes that have the modifier that drops 1-3 scarab (although the bug only occurs when this modifiers rolls 2 or 3 because of rounding) some times the strongbox will not have 75% increased effect and will not drop the extra scarab that would have been granted by the increase (3 scarabs instead of 5, or 2 instead of 3) this does not depend on scarab type and doesn't not depend on map layout or map instance, i have seen it happen,and not happen, on different layouts and on different scarabs. i'd say that about 10-20% of the time this can happen

Screenshot from almost 1 year ago but this still happens:
https://imgur.com/a/Hqtay0H