Did you use down wash? Not using this = dead down.
Did you machine wash or spin it? Spinning = dead down. I either hand wash in bath or use a wool/silk setting on the machine after a soak.
How much have you dried it? A down bag can be dry to touch, with the down still wet. I have a 3 season down bag hanging next to me that was air dried laid flat all yesterday in the sun, tumble dried 3x for 30mins, hung to air and cool each time.
Is it a 3 or more season bag? Big bags can cause problems, and the down wash states ‘get 3, 4 or more season bags cleaned professional/ly’. I have done 3 season bags, but you do have to faff and follow procedure
Mine are cleaned every 5 years or so, as experience says that cleaning kills bags (synthetic and down). Just avoid doing it, and massively air well to avoid smells after use.