On a Mobile Device or any Platform, if you enable a PBR Resouce pack that uses Ray Tracing. And if the device is incompatible. The game will show "Vsync" However, all the text are gone. And it'll cause all inputs to be unresponsive, the only fix is to restart minecraft.

Steps to Reproduce

1. Enable a PBR Resource Pack (Not confuse with Shafer pack)
2. Go to Video Settings
3. Scroll down to Vsync
4. Click on Vsync

Expected Result
Togglable Vsync

Actual Result 
Text disappear and all input will be unresponsive upon clicking on it

This is a minor bug however this can cause devices to have unstable framerate or limit framerate on higher machines. It also unknown if it's enabled or disabled.