Possibly related to the known issue listed in the beta 4 release notes
WidgetKit
Known Issues
Some widgets on macOS, especially those that use App Intents for Configuration, might not work properly the first time the system is started. (109518265) Workaround: Reboot the system before adding Widgets. If you have already added Widgets that are showing empty, delete the Widget, reboot, and re-add it.
I reboot it, it became normal, but it became blank after a while. Let me try the sequence you mentioned here. delete it then reboot it, then add it back