When create an RTX world and turn ray tracing ON everything is black as if texture pack is not loaded. I tried all the worlds but still get the same black textures (see screenshot). 

Minecraft Beta version: v.1.15.0.8

Nvidia driver: 445.87 WHQL Game Ready

Default settings

System: R5 3600, 16GB RAM, RTX 2060 Super, Samsung EVO SSD

Win 10 PRO, Build 1909