Yup, depending on Gatekeeper, you may be running SketchUp from a different location. See this thread: Send to Layout not working in 2017 - #20 by MilesW
If any of that in that thread doesn’t make sense, let me know. I didn’t notice the last comment in there, but this would be my suggestion: go to /Applications/Utilities/Activity Monitor.app and launch it. Search for SketchUp. Double click on it. A window should appear with 3 tabs; click on the 3rd one (Open Files & Ports). If the first few lines don’t have:
/Applications/SketchUp 2017/SketchUp.app/Contents/MacOS/SketchUp
and instead have something like /var/folders/blah blah…
then it’s a Gatekeeper issue. See that thread about doing 'sudo xattr ’ etc… and it should clear.