30% speed elixir

hello can someone explain why it doesnt stack? I tried using 25% lix and 30% speed together only 25% worked. I am using holley set and it says stacking speed in description but why 30% lix dont work with it? This is confusing because I switched from zaarus set and the description of it doesn't say stacking but why both of them have same mechanics with elixir? Is this bugged?

Speed set bonus(ring amu) not stacks with 30% speed elixir

Wysłane z mojego ASUS_I005DA przy użyciu Tapatalka

The 25% speed elixir is part of the HuD elixirs, of which all stack( 25%Damage, Speed , Luck.. on your screen for gold).