My experience as a tank makes me think this is what is happening. Healers are hard locking on a player so that any group type skills will be directed towards that player(hard lock is the little circle above the arrow on top of palyer.) They may switch off to another group member with the intention of casting multiple skills but they did not hard switch to the target. Without hard switching - the first skill will hit the selected player, but the skill cast after would go back to the hard selected target. Playing as a healer the last few nights - I have yet to encounter the issue that is being talked about. I am playing with an xbox 360 controller on a pc for reference.