It is not a bug. It is part of the game. Many FNG Newbs to the Mass Effect series struggle to understand the games. Let me give you some advice on the games as I am a veteran player of all three games and originally started playing the game back when I was still in high school. If you ignore the side quest to actually get the access card from the doctor and complete the hot labs first ALL NPC WILL BE HOSTILE AND YOU are automatically locked out of the quest.
https://www.ign.com/wikis/mass-effect/Hot_Labs
I suggest you revert to a save file BEFORE the save file where you did a huge boo-boo And also follow the walkthrough too. Also if you Cmdr. Shepard is 100% Rouge in Mass Effect 2 and 3 they will sacrifice themselves instead of jumping on the Normandy in Mass Effect 2 Suicide Mission and also take the time to resolve all differences and thoroughly research all upgrades and prototypes BEFORE INITIATING THE SUICIDE MISSION. Also, another thing is DON'T INITIATE THE MISSION UNTIL YOU ARE READY
Because one time I had all 12 members KIA back on the 360 version another time I has 8 and Grunt and Legion were KIA after the long fall. Also it is is crucial that Wrex survives, and Ash doesn't put him down and with a high paragon level you can get him to stand down and you can also get Saren to comit suicide but only if you have convinced him all three times throughout the game.
And there is also a bit of math to hold the line for the assault in the suicide mission. Have Kasumi as the tech specialist and you literally have to be extremely quick and run like hell through enemy fire to all 6 vents and she will survive. By saving the crew and sacrificing the colonists, in Mass Effect 3, you can recruit Daniels and her partner in crime and can save the ship from a massive plasma vent which will kill everyone on the engineering deck ONLY IF YOU GOT THE FIRST UPGRADE IN MASS EFFECT 2 there is also a way to actually successfully end the quarian war and get the geth to make up and get the krogans and Eve (AKA URDNOT BAKARA ) will rally every krogan if the genophage is cured and you are also honest about the STG sabotage.
