It seems that there is an issue with the WebToolbar.
Steps to replicate :
Create a WebToolbar, add it to your page.
Add 8, 10 buttons with icon and text
Load that page in a browser or a tablet .
If screen is to small it will render the last button that fits and then when you scroll to the right to see the rest of the buttons it comes blank, so rest of the menu disappears .
apparently. the issue only happens to Windows this time , it seems that on Macos it renders properly even on small screens, you can scroll and see the menu, while on windows whatever exceeds the current windows it gets cut