In Blueprint Editor, how do I marquee/box/drag select?

I’m in 5.4.

I can marquee/box/drag select Actors in the Main Editor Viewport using CTRL+ALT LMB.

** But I can’t marquee/box/drag select meshes in the BLUEPRINT Editor Viewport **
(not even when I use orthographic views)

How do I mouse-drag multi-select in the Blueprint Editor Viewport window?

Thanks.