A 45-year-old man on ICU is receiving a massive transfusion following a traumatic liver laceration. He has received 12 units of packed red cells, 10 units of FFP, and 2 adult doses of platelets in the last 3 hours. His temperature is 34.2°C, pH 7.15, and ionised calcium is 0.85 mmol/L. What is the most likely cause of the hypocalcaemia?