are you just opening the bleed screws as is or using a pipe n jar?

in using the pipe n jar the fluid should travel upwards from the bleeder. If going downwards or dribbling then you have a very high chance of air getting trapped in the calipers.

I had this on my W124. new brake flexible hoses, new fluid and a good bleed through fixed it right up.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)