When it comes to the end of a stack. it leaves a "Phantom" crushed ore in the Input Bus that cannot be manipulated by anything or deposited, but can be removed from the Input Bus into the inventory (only with click-and-place, shift-click does not work). This also means that, whenever a stack of 1 is placed, it instantly becomes a phantom crushed ore, and it does not output a crushed ore.

• Observed in GT++ 1.6.99
• GregTech 05.09.32pre1 environment

Sounds much like 0 size stack