When I killed General graardoor his drop spawned like 4-5 centimeters away. and I was unable to pick it up. the magic/range attacks from the minions are also not on the spot where the minions are.
Later I killed the minions and the same problem occured. When I relogged, was able to pick up the drops. not sure if this happens everytime because I wasnt able to kill it twice

It's likely that your position was out of sync. You can see that because the yellow projectile of the bandos minion is starting not from its position. This error fixes itself if you walk somewhere. I'll see if I can do something that it fixes itself when you don't move.