Nginx reverse proxy setup zabbix white site

Hello,

i try to reach my zabbix server behind a nginx reverse proxy. Login Screen is loading, but after login i get a blank white site.

nginx reverse proxy setup: External address: https://mydomain.com/monitor

location /monitor/ {
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_pass http://ip/monitor/;
}

Setup Nginx Webserver (simple setup to test reverse proxy),
/usr/share/zabbix is linked to /var/www/html/monitor


server {
listen 80;
server_name ip;
root /var/www/html;
...
location ~ \.php$ {
include snippets/fastcgi-php.conf;

# With php-fpm (or other unix sockets):
fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
}
internal access with login is ok: http://ip/monitor.

I am grateful for any help. Thanks