Not sure if this helps. My HDMI through a multi function USB-C device (Network, USB and HDMI) stopped working after 11.4 upgrade.
I have a second monitor working through a Display cable to a USB C adapter. So I am not using HDMI and I am not using the multi function USB-C adapter for display. The USB and Network still continued to work.
Years ago, I had a case where an update stopped third party adapters from working but an Apple brand adapter would work. What a pain.
Good luck.
MatthewDoughertyNJ
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