Last week we've migrated our site from http to https. Since then our rankings disappeared and traffic drop by 90%.
Now we are using SEMRush to scan our site and received the following notice,
No redirect or canonical to HTTPS homepage from HTTP version
which seems to be the main issue. However, our site is indeed already on https, but it seems Google cannot tell that we have moved.
Can you give us suggestion on how to inform our developer to fix this issue? Thank you.