It looks like the game turns raytracing OFF by default when creating /loading a world (with a Raytracing pack). Even though in settings it appears enabled.
Possible workaround:
Press ; (on the keyboard 2x) to switch raytracing ON while in the world. This might cause another bug where the graphics are all glossy. Reload the world.
(Note: this has to be done every time you relaunch the game)

Downloaded the beta and started using RTX Minecraft. Wanted to tinker with the DLSS Settings, but Advanced Video Options is missing.

Uninstalled/reinstalled, reset Minecraft settings, rebooted device. Advanced Video Settings still missing.