Kennet I remember running across this scenario in MS Project 2013 when I was experimenting with load patterns. In those experiments, I found that Project only adjusted the assigned resource that was driving the task completion date/time. And as you’ve noticed, the other resources kept their prior allocation. My assumption was that this is how Project is designed and since it wasn’t causing us any problems, I didn’t pursue it any further. So, while I can’t definitively explain why Project works this way, I can say that I have also seen this in 2013.