Hi,
Please put in SSL DNS verification in SS. The problem I faced is I usually setup the domain and enable Cloudflare proxy immediately before installing SS in the server. I will never off proxy therefore the only way to get SSL verified is via DNS. Even if I off proxy to get initial SSL, then on proxy, after 3 month I need to off and renew the SSL again which is a bit of hassle as I have lots of website. This is for single WP, not multisite.