Unable to get 4K HDR Output from iPad Pro 2018

I've been trying to get 4K HDR output from my 2018 iPad Pro using various combinations of adapters and HDMI cables, but have not been able to succeed yet. Looking for some help and guidance from someone who has been successful here.

Hardware:

1. 11" iPad Pro 2018 256GB
2. LG B7A OLED
3. Cable Matters USB-C to HDMI Adapter (https://www.cablematters.com/pc-1053-125-aluminum-usb-c-to-hdmi-adapter-4k-ready.aspx)
4. Monoprice High Speed HDMI Cable (https://www.monoprice.com/product?p_id=24187)

I have tested the combination of the adapter and HDMI cable with my ThinkPad which is able to output in 4K and in HDR to the TV without any issues. No success thus far with the iPad Pro.

Looking forward to hearing from all of you!