I have a Dell AIO 7450 with an Intel HD 630 with HDMI IN. All drivers and BIOS are up to date. I am trying to project my MacBook Air to the Dell AIO. I have tried two different dongles and two different HDMI cables. I have used HDMI on other monitors and it works fine. When I connect the MacBook Air it can see the Dell and it shows the monitor as connected. I called Dell support and they were useless. I called Apple support and through the support tool they can see display going to the HDMI connection. I am not sure on the Dell AIO 7450 who controls HDMI in? I assume Intel? Also I am not sure if a need HDMI software to see the incoming HDMI? I did not see any BIOS, Windows or Intel settings for HDMI in.
I figured it out. I feel embarrassed but dell should feel more embarrassed. after 7 phone calls to Dell and talking with 5 different reps and 2 supervisors i finally discovered there is an input button on the side of the AIO 7450. You just press the input button like a TV and it changes the source to HDMI 1. The button is not labeled and does not stand out. It does not appear that Dell has OSD software that shows the HDMI connection on the screen - just the manual button.
I miss the old Dell that had a support team that actually knew how the product worked. Now the outsourced untrained support team just looks for excuses to point the finger at the customer.