Graphs are not loaded behind proxy

HI there.

I have grafana instance launched in docker container behind nginx proxy

docker run --restart=always -d --name=grafana -p 3000:3000 -v grafana-data:/var/lib/grafana grafana/grafana

Added to grafana.ini accroding to the article next values (domain particularly):

[server]
# Protocol (http, https, h2, socket)
protocol = http

# The ip address to bind to, empty will bind to all interfaces
;http_addr =

# The http port  to use
http_port = 3000

# The public facing domain name used to access grafana from a browser
domain = grafana.mycompany.com

# Redirect to correct domain if host header does not match domain
# Prevents DNS rebinding attacks
;enforce_domain = false

# The full public facing url you use in browser, used for redirects and emails
# If you use reverse proxy and sub path specify full url (with sub path)
root_url = %(protocol)s://%(domain)s:%(http_port)s/

# Serve Grafana from subpath specified in `root_url` setting. By default it is set to `false` for compatibility reasons.
;serve_from_sub_path = false

# Log web requests
;router_logging = false

# the path relative working path
;static_root_path = public

# enable gzip
;enable_gzip = false

# https certs & key file
;cert_file =§
;cert_key =

# Unix socket path
;socket =

Set up nginx reverse proxy:

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


server {
    listen 443;
    proxy_read_timeout 3600s;

    large_client_header_buffers 16 32k;

    ssl on;
    ssl_certificate /etc/nginx/conf.d/ssl/grafana.crt;
    ssl_certificate_key /etc/nginx/conf.d/ssl/grafana.key;
    ssl_session_timeout         5m;
    ssl_protocols                       TLSv1 TLSv1.1 TLSv1.2;
    ssl_ciphers                         HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers   on;
    server_name  grafana.mycompany.com;

    access_log            /var/log/nginx/grafana.access.log;

     location  / {
      client_max_body_size    100M;
      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_send_timeout      600s;
      proxy_read_timeout      600s;
      #proxy_redirect           off;
      proxy_pass http://localhost:3000;
    }

}

    server {
      listen 443;
      server_name grafana;
      return 301 https://$server_name.mycompany.com$request_uri;
    }

Interface is shown but graphs are not loaded (see screenshot)

)

Logs show no errors when I requested data:

t=2020-10-19T17:15:17+0000 lvl=info msg="Request Completed" logger=context userId=1 orgId=1 uname=admin method=GET path=/api/datasources/proxy/1/api/v1/query_range status=301 remote_addr=xxxxxxtime_ms=1 size=185 referer="https://grafana.mycompany.com/d/_NNAgsPZk/teamcity-cloud-agents?orgId=1"

t=2020-10-19T17:15:17+0000 lvl=info msg="Request Completed" logger=context userId=1 orgId=1 uname=admin method=GET path=/api/datasources/proxy/1/api/v1/query_range status=301 remote_addr=xxxxx time_ms=2 size=185 referer="https://grafana.mycompany.com/d/_NNAgsPZk/teamcity-cloud-agents?orgId=1"

t=2020-10-19T17:15:17+0000 lvl=info msg="Request Completed" logger=context userId=1 orgId=1 uname=admin method=GET path=/api/datasources/proxy/1/api/v1/query_range status=301 remote_addr=xxxxxxx time_ms=1 size=185 referer="https://grafana.mycompany.com/d/_NNAgsPZk/teamcity-cloud-agents?orgId=1"

t=2020-10-19T17:15:17+0000 lvl=info msg="Request Completed" logger=context userId=1 orgId=1 uname=admin method=GET path=/api/datasources/proxy/1/api/v1/query_range status=301 remote_addr=xxxxxx time_ms=2 size=185 referer="https://grafana.mycompany.com/d/_NNAgsPZk/teamcity-cloud-agents?orgId=1"

Though http works fine.
Stuck on this. Any idea what this issue is about ?
Thanks in advance