Icons greyed out on write a page or post

I had the same problem. I had WP installed on a subdomain, and on the Settings page, had both the WordPress address and Blog address as https://www.subdomain.com.

On a lark I changed them both to https://www.mydomain.com/subdomain and voila! all the icons appeared. Not sure why it worked, but it worked.

Hope it works for you too.

-Martin

Wait!

When I then tried to visit https://www.subdomain.com it redirected me to https://www.mydomain.com.

Back into Settings: changed Blog Address to https://www.subdomain.com, but left WordPress address as https://www.mydomain.com/subdomain and it worked again.