Chosen Solution
Hello, I have this problem at my work with my MacBook Pro 2018. While connecting to projector with 15m HDMI cable via USB-C hub I get no input on projector, but my Mac finds the projector and I can even change resolution of projector. Then when I took a shorter cable my Mac suddenly started to mirror display. All windows laptops works perfectly with that projector and most Mac’s do as well. Tried different USB-Chubs no help, and I had same problem with two different Projectors and two different MacBook Pro’s both the newer 2018 model.
After booting completely and with the external plugged in hit Command and F1 keys at the same time.
I don’t have the latest mac, but sometimes they don’t get connected automatically to an external display. If that happen, you should check the section of displays in settings, and select it.
