MCLiquidStack.matches() uses getDefinition().equals(liquid.getDefinition()). However, MCLiquidDefinition does not extend equals(), and getDefinition() always creates a new instance of it - in other words, this will always return false, and two liquids will never match.

Please note, you will be treated exactly like any other person who submits a bug report, saying this, if you decide to delete this template entirely, your issue will be closed.

I dare you, Jared. (In my defense, (a) I do not think the template is in any way necessary for a strictly technical issue report, and (b) I did not delete it entirely.)