Mg dropping despite supplementation

Hello.

Been taking magnesium for months, last 3 with a daily consistent 650mg day (400mg from supplement rest from food) and what the labs show that somewhat is not being retained. What is going on? Been taking Magnesium Bisglycinate.

Listed in photo by order:

Ionized Calcium

RBC Magnesium

Ionized Magnesium

Serum Magnesium

Vitamin D3

Ionogram

Labs