DELL WD15 start up problem with Lattidude 5480

Hi All,

in the afternoon we always switch off all the power in the office (switchable power-strip). After power on the strip I'm not able to start up my Dell 5480 by pressing the power button on the WD15. Even if a power up the notebook directly the WD15 is not alive. I always need to re-plug the USB-C cable into the notebook and than it works. It's a pain in the ....:(

Has anybody the same problem or suggestion?