Hello Rui,
Kindly share your site URL along with your WordPress credentials(username and password) on our support email id: [email protected], so we will directly check on that.
Thank you.
I have solved this problem. Just in case someone else run into this issue. Here is the fix.
The problem is caused by a WordPress plugin Wordfence Security installed at the parent or root domain level, it affects the subdomains. I had to disable the plugin at the parent domain level, after that, i successfully added the map code at the subdomain.