I had similar problems with my XPS 9560 laptop with Killer card. XPS 9560 could not see 5 GHz Wi-Fi most of the time (I had to reboot the system to see it). Then I found out that my Asus router automatically set up Wi-Fi chanel which is not seen by my Galaxy S6 phone (chanel 140 or so). I set chanel 40 manually and now both Galaxy S6 and XPS 9560 can see 5 GHz Wi-Fi. So it looks like some Wi-Fi bands are badly supported by Killer card which is weird in 2017 (by the way my iPhone and iPad see all 5 GHz chanels despite being made in 2016).