Is anyone having issues copying materials? ctrl+m
Ctrl+M is used for copying geometry and objects (components and groups), not for copying materials. It has never been used for copying materials. And in 2021.1 it’s a toggle function for copying with the Move tool. Press and release to activate the Copy feature.
Watch the statusbar on the bottom closely (maximize the SketchUp window) the modifier for ‘sampling’ is Alt on Windows, Cmd on Mac.