Hi Samuel,
Thanks for your reply. I don't understand what you mean about sending you a terminal, but I copy/pasted what comes up in the error box on my screen. Also attached a screen grab. I see several Mac users have posted the same error message, we are all having a consistent problem. I am on Mac OS 10.15.4 Sketchup Pro 2020. Thanks.
Universal Importer Error: Command failed: "/Users/dawn/Library/Application Support/SketchUp 2020/SketchUp/Plugins/universal_importer/Assimp/Mac/assimp" info "/Users/dawn/.UniversalImporter/tmp/import.fbx" > "/Users/dawn/.UniversalImporter/tmp/assimp.nfo"
/Users/dawn/Library/Application Support/SketchUp 2020/SketchUp/Plugins/universal_importer/assimp.rb:166:in `get_texture_refs'
Universal Importer Version: 1.1.5