So I was just running Garden of Salvation Raid and when we got to the 3rd damage phase, the box above the pillar to start the tether was bugged. We were shooting it and it was saying immune even though we had killed the Hydra (that causes the immune box around it). We had it happen to us twice when we got to the third damage phase. This is extremely annoying because we would have finished the raid twice, but we unable to do the tether to the boss. (FYI, I have the enlightened title and am very knowledgeable about the raid mechanics, I know that you can't tether the boss if the pillars aren't full because of vex sac's or you don't get enough motes. This is a legit bug)