The AdaptiveToolBar does not display all items in the overflow section (more buttons) when there are Buttons with Visibility set to false.
Run the REPL snippet
Shrink the window size so that the toolbar is narrower and some buttons are hidden
Open the Overflow list
Refresh and Refresh All buttons are missing from the list
Buttons with Visible=false parameter should not affect the overflowed button collection.
All buttons that are Visible=true and overflowed should be available in the more buttons section.
All
All
When Adaptive = true, changing the collection of buttons seems to "break" the adaptive calculation. The Toolbar fails to determine what are the buttons to show in the main element and what are the buttons to show in the pop-up: https://blazorrepl.telerik.com/wSubOWlS08FLz7aZ54
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ADMIN EDIT
For the time being, a possible workaround is to force the component to refresh when you change the buttons. For that purpose, you can dispose it and re-initialize it after some delay. Here is a runnable sample: https://blazorrepl.telerik.com/QIOFuCvS400o5tfL34.