AoA Sir I'm also facing the same issue in my Suzuki Swift dlx 2010.I had changed the brake oil,Master Cylinder but the brake issue remains same ,there is no oil leakage from any brake pipe,the brake pads are Ok,After pumping the brake pedal 3 to 4 times the brake works normally..
This problem occurs after driving about 50 to 60kms and mostly on bumpy roads
If anyone has knowledge about this problem then plz guide me.