Although we haven't experienced this specific bug of dying from fall damage between platforms, we HAVE encountered a different bug on 16 man HM similar to this. When intentionally falling off platforms with the intent of respawning back at the top, people end up dying from fall damage when prior to the latest patch they would be alive. We do not know yet if this is a bug ot intended but it holds true on every single platform except the four that the tentacles spawn on. Even on those four platforms when people jump off to reset at the top they occassionally die leading us to believe it is a bug.
Had to change our approach yesterday, instead of jumping off to reset debuff me and my tanking partner decided to just go hop all the portals back because it was killing us. When other people tried two died, one succesfully went back to home.
Either say it's not the intended way and it will kill us from now on or change it back to how it was, changing stuff like this without a word is really depressing.