Grafana stuck on loading screen

I've installed Grafana behind Nginx running as a reverse proxy for it and then behind Cloudflare. Unfortunately when I am trying to access it is stuck on jumping Grafana logo with "loading" inscription underneath it.

Grafana is expected to be accessible on subdomain like grafana.domain.com.

I've tried to change a config in both Nginx vhost and grafana.ini but with no luck. My current Nginx config:

server {
        listen 80;
        server_name grafana.domain.com;
        return 301 https://$server_name$request_uri;
        }

server {
        listen *:443 ssl http2;
        server_name grafana.domain.com;

        ssl_certificate /etc/ssl/cert.pem;
        ssl_certificate_key /etc/ssl/key.pem;
        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
        ssl_session_timeout 1d;
        ssl_session_cache shared:MozSSL:10m;
        ssl_session_tickets off;
        ssl_prefer_server_ciphers off;
        resolver 1.1.1.1 8.8.8.8;

        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "no-referrer-when-downgrade" always;
        add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;
        add_header Strict-Transport-Security "max-age=15552000; includeSubDomains; preload" always;

        proxy_redirect off;
        client_max_body_size 100M;
        proxy_read_timeout 3000s;
        proxy_send_timeout 3000s;

        access_log /var/log/nginx/grafana-access.log;
        error_log /var/log/nginx/grafana-error.log warn;

        location / {
                allow 1.2.3.4/32;
                allow 2.3.4.5/29;
                deny all;

                proxy_ssl_verify                        off;
#                proxy_redirect                          off;
#                proxy_hide_header                       Upgrade;
                proxy_set_header Host                   $http_host;
#                proxy_set_header X-Real-IP              $remote_addr;
#                proxy_set_header X-Forwarded-Host       $host;
#                proxy_set_header X-Forwarded-Server     $host;
#                proxy_set_header X-Forwarded-For        $proxy_add_x_forwarded_for;
#                proxy_set_header X-Forwarded-Proto      $scheme;
#                proxy_set_header X-Server-Address       $server_addr;
                proxy_pass                              http://localhost:3000;
#                proxy_http_version                      1.1;
#                proxy_cache_bypass                      $http_upgrade;
#                proxy_set_header Upgrade                $http_upgrade;
#                proxy_set_header Connection             "upgrade";
#                proxy_set_header X-Forwarded-Port       $server_port;
        }
}

I've also tried changing Grafana configuration to:

[server]
;protocol = http
;http_addr =
;http_port = 3000
domain = grafana.domain.com
;enforce_domain = false
root_url = %(protocol)s://%(domain)s:%(http_port)s/
serve_from_sub_path = true

but that doesn't work either.

In case you disable CF proxy and able to access Grafana, try the following port instead --> 2087