Material dropdown not working with Block edit panel in different screen?

In Block Edit mode, the material dropdown in Properties: Material doesn’t work if the Block Edit panel is in a different screen (I’m using total 3). If I move the Block Edit panel to the same window where Rhino is in, then the dropdown works. That’s unfortunate because the Block Edit panel is just in the way in the main screen with Rhino.

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This bug doesn’t always happen. But when it happens for some reason, and the dropdown menu is not working, moving the Block Edit panel to the same screen as Rhino fixes it.