TPS22918EVM: big drop voltage between IN and OUT even it doesn't have current flow when power start-up

Hello

My customer use TPS22918EVM, main power supply is VCC is from mainboard, it will generate to 1.2V firstly, then generate normal 3.3V VCC , VCC power to another IC NT 51625, NT51625 power part include boost VDDA, positive charge pump  VGH and nagetive charge pump VGL, my customer want to limit inrush current, so use TPS22918EVM series in VCC net, but after add TPS22918 the TPS22918 out voltage have 1.4V drop,at this time, the back circuit havn't work yet, and input current is also 0 mA, so how lead to this drop on TPS22918evm(discharge pin is floating)