Password Protect not working

I’ve tried Password Protect on two websites. For some reason, once the password is entered, the page refreshes but keeps the password field and button instead of revealing the content.

Inspector indicates (in Chrome and Firefox) that the password collection is insecure because our site doesn’t have an SSL cert yet. Could this error be the reason the password doesn’t work? Or should I be looking into theme/caching confllicts?

Thanks!