When using K for brushes, last used brush shows but when you go to use it, it changes to "custom"

Hey, is this possibly a bug since some versions ago? 

I remember that when you used to use the K shortfut for brushes, it would pull up the last used brush and you could just start using it right away without having to re-select it. NOW when press K last used brush does show BUT as soon as you actually go to use the brushes (ex. paint over a face for face smoothing), the brush selection changes to "custom" which does nothing. You have to re-select the brush you want applied. It's kinda frustrating, it's added a few clicks every time I need to use brushes (which I use a lot during editing weddings). 

Could we look in this and see if it's a bug? It should be "loading" a most recently used brush ready to use to save extra clicks. 

Thanks!