SSL not working on multisite (except on a sub-site, which is domain mapped)

My WP Multisite is a sub-directory multisite, so I shouldn't need a wildcard DNS to fix this issue. The SSL worked before I migrated the site to a new domain (same host). I got a new SSL for the new domain, and turned off the old domain's SSL (just in case). SSL still not working. Please help! Thank you!

Here are two screenshots on the issue:

https://www.whynopadlock.com/results/fdbac1f2-2e98-413f-a6f8-34d39d6fa09e

https://cdn.discordapp.com/attachments/529410522521534464/529410817905655818/Screenshot_20181231-232926_Chrome.jpg