So here the scenario. My buddy is doing a 2* SB craft using Maker's Mark + Flawless Synthesis. He miss-manages his CP and ends up down at 12 CP. Flawless Synthesis requires 15 CP to activate and thus he could not press it.

But, under Maker's Mark
Reduces Flawless Synthesis CP cost and durability loss to 0. Effect duration determined by recipe difficulty.
Available only on the first step.
So, is it bug that he could not activate Flawless Synthesis in that situation?