I did not know about the get all drop all commands. There is a match for the drop handball that might override the adventuron default logic. I will investigate but I can’t promise that I will fix this one.
drop all will be matched by adventuron, then all droppable items you hold will be submitted as individual commands (each consuming one tick). Having a custom handler shouldn't affect the item in a get all any differently to dropping it individually. There was a bug where in this area which coincidentally was fixed (hopefully) yesterday in beta 28.
Please retry with the recent version.