I have been mutli selecting tasks, then changing priority via the hotkey p while selected. This works fine most of the time, but sometimes it gets confused.

Exp:
two medium priority tasks listed in main window, both selected, hit p once to promote to high, one goes to low and one goes to high. this is very annoying and a waste of my time to redo the one that didn't work. It does not do this every time, but I would say two thirds of the time