Image Optimize Field - adding ImOp field to a volume causes images in that volume to not be found
Worked with @andrew.welch and found that, although our site is using /html for the webroot, there also existed a /web folder.  For a reason not yet identified, the plugin brought the /web folder to the surface as it was attempting to look in that folder.  I simply deleted the /web folder, and everything works.  

The file craftcms/cms/src/console/Request.php sets the path based on what folders it finds on the filesystem, and "web" is before "html" in the array that it checks

    foreach (['web', 'public', 'public_html', 'html'] as $folder) {
        if (is_dir($dir . DIRECTORY_SEPARATOR . $folder)) {
            $dir .= DIRECTORY_SEPARATOR . $folder;
            break;
        }
    }


Thank you Andrew!