U2518D, HDR dims and brightens

Hi,

I'm having an issue with my U2518D that I've noticed couple of other users reporting, the screen dims and brightens at around 1 minute intervals when in Smart HDR mode. I've looked around the web for users experiencing similar issue, and only this model seems to be affected. Is there a fix for this (Firmware M2T103), or is it a defective unit?

Regards