Trying to create installer- exits after brief start when select USB drive

I tried different downloads of macOS installers. I got those downloading and extracting fine. When it asks if I want to create the installer, I select my USB drive (tried 2 new sticks already, both larger than 16gb), I see the window open, brief progress bar, and it exits, with no error message to lead.

Anywhere to look on whats happening?

Thanks