Permission name for the widget is panel.widget.widget

[samuba]

If you have in your Kirby Role the wildcard permission set to false ('*' => false) you have to set the permission for this widget explicitly.
Unfortunately that would look like this at the moment: 'panel.widget.widget' => true
Which is pretty nasty because you dont know what widget that actually is and you get serious problems if another widget you use did the same mistake.

For reference and context, here is the discussion I had with texnixe on the topic:
https://forum.getkirby.com/t/widgets-are-auto-hidden-when-permission-is-false/9758