Hi AMD support.
Running Win update 1903 + AMD driver 19.6.3 (and below), I lost many resolution options like 3200 x 1800 to my UHD TV (4K LG OLED).
This is happening on both my systems (one with Vega 56 and one with Radeon VII). So it's driver related.
The 4K monitor can go to 3200 x 1800 and has all possible resolutions. But on 4K TV, it's only about 3-4 resolution options (1080p, 1440p and 4k + 1 or 2 odd ball resolutions ). I have tested with HDMI, 4K Displayport-to-HDMI adaptor... same deal. Monitor and TV running via. HDMI but TV isn't getting the resolutions.
I had to revert to previous Windows 18xx update, and install 19.3.4 driver, to get that resolution back to my TV. It has always worked with every driver on my Vega 56 and Radeon VII. The 19.3.4 is the latest non-broken driver.
So something has gone wrong and I am now not able to update, since I bought the Radeon VII to play at higher resolution then 1440p on a 4K tv, but Radeon VII is not able to produce 60fps at UHD 4K, I have to go to 3200 x 1800 to gain A LOT fps for steady 60fps. Yes I am always running the option settings to give the most FPS vs. EYE CANDY.
I have done completely "DDU" driver cleaning, and came out with the same results. As soon as I reverted back to previous windows 1800 and older drivers (19.3.4 and below), voila!... the resolutions are back.
Please respond, and report back to your tech / driver / software team. It's very easy to test.