The OnePlus 7 Pro is not an officially supported device at this time and may not work with annotations. You can find a full list of supported devices here: https://chalk.vuforia.com/content/vuforia-chalk/en/download-chalk.html
The default setting for unsupported devices is A/V only mode. You can override this setting and try to use annotations by selecting 'Audio-Video with Live Annotations' under the App settings.
We are actively working to expand our Android device support list.
