I'm having the same symptoms with my 2017 GT that I just picked up... notice that the headlights are on all the time, even when it's set to 'Auto' for the lights... the rears do NOT light up though, so it's not the ambient light sensor, in that if it thought it was nighttime the rear lights would also turn on. I've played around with the various headlight settings with the car and nothing has seemed to change it. I actually had to travel a good distance to pickup the car, so I haven't brought it to the dealership to look at... was wondering if you (or anyone else) has any progress on this. I guess from a safety perspective it's not any worse, but I love the look of the DRL's on it that I hate that it mutes them during the day.
One question - Did you get a GT with or w/o the premium package. I just ask because mine is w/ premium... trying to determine if (not sure why it would make a difference) it's something with premium trim only.