On level 4 ankou, after the script has been running a while it has a tendency to start leaving drops on the ground. Saw death runes and blood runes disappear a couples times.
Okay so what is happening is this.
1) inventory full with half peaches, half bones, and some drops.
2) blood runes on ground
3) leaves blood runes attacks next ankou
4) attacks next ankou....attacks next ankou....attacks next ankou.....
5) eats peach
6) picks up bones to fill blank spot
7) picks up blood runes
Basically if you have full inventory using b2p it wont pick up drops until it needs to get more bones.