same, I just got my Mac mini and when connecting it through usb-c I get full resolution on a Dell U4919DW however when using hdmi, I get 3840x1080, same cables connected to a multi av adapter to my MacBook Pro 2018 I get full resolution. What is most interesting is that if I use the same multi av adapter on one of the usb c ports I only get noise on the screen. I updated it to the latest version but still the same problem.