Thanks again, Dave. My computer is old by technology standards, but does meet/exceed requirements. And yes, the Edit Texture dialog comes up and shows a preview of the texture, but only when I choose the duplicate and edit texture option. Trying to create a new texture from the Resource Manager simply closes the RM window. I am able to create new hatches and other options from the drop down menu. Another thing that happens after duplicating and editing a texture, the preview/thumbnail in the RM and in the Object Info window look corrupted. (see attached screen shot, specifically the Grass Cloth textures created today). It's hard to not associate these new problems with my recent "upgrade" to Mac Big Sur, though it could be coincidental.