Nginx Reverse Proxy Won't forward JSON over 100K

I have an Nginx reverse proxy that forwards to a Node.js Express server. Everything works fine unless the JSON payload is over 100K. The node function receives an empty body. I've tried setting the Nginx client_max_body_size to 10M, even though the default is 1M. No errors in the Nginx logs or error logs.

The Nginx Conf file:

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
        worker_connections 1500;
        # multi_accept on;
}

worker_rlimit_nofile 3000;

http {
        ##
        # Basic Settings
        ##
        proxy_read_timeout 600;
        proxy_connect_timeout 600;
        proxy_send_timeout 600;

        client_max_body_size 10M;

        sendfile on;
        tcp_nopush on;
        tcp_nodelay on;
        keepalive_timeout 65;
        types_hash_max_size 2048;
        # server_tokens off;

        # server_names_hash_bucket_size 64;
        # server_name_in_redirect off;

        include /etc/nginx/mime.types;
        default_type application/json;

        ##
        # SSL Settings
        ##

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
        ssl_prefer_server_ciphers on;

        ##
        # Logging Settings
        ##

      access_log /var/log/nginx/access.log;
      error_log /var/log/nginx/error.log;
        ##
        # Gzip Settings
        ##

        gzip on;

        # gzip_vary on;
        # gzip_proxied any;
        # gzip_comp_level 6;
        # gzip_buffers 16 8k;
        # gzip_http_version 1.1;
        # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

        ##
        # Virtual Host Configs
        ##

        include /etc/nginx/conf.d/*.conf;
        include /etc/nginx/sites-enabled/*;
}

Site config

server {

        # SSL configuration
        #
        # listen 443 ssl default_server;
        # listen [::]:443 ssl default_server;
        #
        # Note: You should disable gzip for SSL traffic.
        # See: https://bugs.debian.org/773332
        #
        # Read up on ssl_ciphers to ensure a secure configuration.
        # See: https://bugs.debian.org/765782
        #
        # Self signed certs generated by the ssl-cert package
        # Don't use them in a production server!
        #
        # include snippets/snakeoil.conf;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name api.site.com;
        client_max_body_size 10M;
        location ^~ /assets/ {
                gzip_static on;
                expires 12h;
                add_header Cache-Control public;
  }

location / {
       proxy_set_header X-Real-IP $remote_addr;
       proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
       proxy_set_header X-NginX-Proxy true;
       proxy_pass http://localhost:5000;
       proxy_set_header Host $http_host;
       proxy_cache_bypass $http_upgrade;
       proxy_redirect off;
       client_max_body_size 10M;
 }

And I'm doing a very simple POST with node-fetch a very simple fetch call. When the body is less than 100K all good, when over the data isn't passed by the reverse proxy:

const options = {
    method: "POST",
    mode: "cors",
    headers: { Accept: "application/json", "Content-Type": "application/json" },
    body: JSON.stringify(body),
  };
fetch(`https://site`, options);