Can't link to imported Textures in Material Instance Editor

So I’ve opened the Material Instance Editor for a material I need to edit.
I simply want to change the default Normal, Roughness and Base Color maps.
I’ve also imported my new Textures by dragging them into my Content Browser.

But no matter what I do I cannot link to any of these imported textures! They do NOT come up in the Browse.Search Assets field.

Spent a couple hours googling. What am I doing wrong?

Import them using the import menu, rather than dragging them…