My LG C1 OLED, supports all formats but HDR10+ , but when I run the test on the newest AppleTV for unverified formats, none work and switches back to 4K SDR. Why is this not working?

Verify your HDMI connection and HDMI settings.

• Use HDMI cables rated as 48 Gbps “Ultra High Speed”, suitable for all HDMI 2.1 features.
• When using 18 Gbps “Premium High Speed” HDMI cables, bandwidth will be limited to HDMI 2.0 standard, and you’ll need to apply settings (YCbCr 4:2:0) to allow other high end video properties, like HDR and Dolby Vision.
• Select TVs may need to configure each selected HDMI port for high bandwidth use, including HDR and DV. LG calls this ‘HDMI Deep Color’. See your TV manual.

Hello bigbronco5,

Welcome to Apple Support Communities!

We see you viewed the Apple Support page for Turn on Match Dynamic Range or Match Frame Rate on your Apple TV - Apple Support

We want to help get your Apple TV and using the best possible format for your TV.

Try restarting both devices then trying to run the test again:

"If Apple TV can't determine which display formats are available

Verify which formats your television can display. To verify a format, go to Settings > Video and Audio > Match Content. Then select a format under Unverified Formats to run a short display test and verify that it displays correctly on your television."

Detailed on the Apple Support page you linked.

Check for updates to your Apple TV if the issue remains:

"Update your Apple TV manually

1. Go to Settings > System > Software Updates and select Update Software.
2. If there's an update, select Download and Install. 
3. Wait for your Apple TV to download the update. Keep your Apple TV connected and plugged in to power until the update is complete.

After the update downloads, your Apple TV will restart, prepare the update, then install it. When the update is complete, your Apple TV will automatically restart again."

This Apple Support page has the full details: Update your Apple TV - Apple Support

We hope this helps to isolate the issue so you can view the highest possible quality with your Apple TV.

Cheers!