Commands block glitch

Hello there mojang team people. I am here reporting this weird command block glitch that keeps killing my mobs when I try to buff them. I'm not sure why it does this but if I try to buff a mob with more than 4 buffs, it's just kills them and it's very frustrating because now my hard work making this boss fight adventure map went to crap because I can't make strong "bosses" With out them dien instantly when I hit the commands to buff them. If this gets fixed I would be super greatful. Ik a lot of people complain about bedrock a lot, but man, I hope u guys fix this plz, my 60+ hours went to the dump lol. Love the game and you guys.