This has been fixed in BPS .51.8. The issue is when you first login to your site you have a literal URL of: /wp-admin. So for now click on the WordPress Dashboard link to get an URL like this: /wp-admin/index.php or any other link in your Dashboard and the Dismiss Notice will be dismissed correctly.
Code in BPS .51.7:
if ( esc_html($_SERVER['QUERY_STRING']) == '' ) {
$bps_base = basename(esc_html($_SERVER['REQUEST_URI'])) . '?';
} else {
$bps_base = str_replace( admin_url(), '', esc_html($_SERVER['REQUEST_URI']) ) . '&';
}
Code in BPS .51.8:
if ( esc_html($_SERVER['QUERY_STRING']) == '' && basename(esc_html($_SERVER['REQUEST_URI'])) != 'wp-admin' ) {
$bps_base = basename(esc_html($_SERVER['REQUEST_URI'])) . '?';
} elseif ( esc_html($_SERVER['QUERY_STRING']) == '' && basename(esc_html($_SERVER['REQUEST_URI'])) == 'wp-admin' ) {
$bps_base = basename( str_replace( 'wp-admin', 'index.php?', esc_html($_SERVER['REQUEST_URI'])));
} else {
$bps_base = str_replace( admin_url(), '', esc_html($_SERVER['REQUEST_URI']) ) . '&';
}