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MacBook Air is not listed as being necessarily compatible with HDMI usage. Or, you may need a differing adapter... MacBooks' outputs are not standardized to being identical, but rather must be approached on a one-by-one basis, according to the individual aspects.
Where is the port on your Apple Air 2016, that you call the USB/HDMI connector, please?
Or, are you using a USB port on the Apple Air 2016, to go through a USB-to-HDMI adapter cable, to an HDMI input on a monitor? That may simply not work, until the USB is configured to produce video output (there's no reason for a USB port to produce video output per se, until it is specifically configured to do so, you see.)
Are you using the USB 3 to HDMI adapter cable with this USB/HDMI connector on the Apple Air 2016 ?
Please give me more details, and I will try to advise you through to a good solution.