Legion bug(?)

I've just had this happen in like... my second map of this league. I'm not exactly sure what caused this but rare legion mobs (Sergeants) just died instantly instead of getting released from stasis, dropping their items before the time was even up.

Video: https://medal.tv/games/poe/clips/14qEW9fAUQbcd3/d13370Iggg5G?invite=cr-MSwzaG4sNzk1Mzk0OCw

i have same thing, and whenever i ask about itm either no body knows, or just dont want to answer, i still dont understand if its a new feature or a bug >.<

edit: i thought maybe its a bug with explode from inpulsa that i use, but not sure.