NGINX - 404 errors after caching static (CSS/JS) files - nginx

Question

I am trying to setup nginx to cache my static files, such as jpg, jpeg, css and js.
The following is what my nginx.conf (not nginx.conf.default) looks like
events {}
http {
server {
listen 3000;
# listen 443 ssl;
server_name localhost;
# Set the SSL header only for HTTPS requests.
if ($scheme = "https") {
set $ssl_header SSL;
}
error_page 401 = #error401;
client_max_body_size 1000M;
# Expire rules for static content
location / {
# HTTPS header.
proxy_set_header X-Proto $ssl_header;
proxy_set_header Host $host;
proxy_set_header Client-IP $remote_addr;
# Redirection host.
proxy_pass http://localhost:300x;
}
location ~* .(jpg|jpeg|css|js)$ {
expires 1d;
access_log off;
add_header Cache-Control "public";
}
I have then tried to add the following to cache:
location ~* .(jpg|jpeg|css|js)$ {
expires 1d;
access_log off;
add_header Cache-Control "public";
}
I get 404 errors for all my CSS & JS files. My JPG and JPEG files get cached. I have tired adding in the root directory here, and the in location \ {} block. This does not seem to make a difference.
I have tried many different configurations - I just want to know how to cache my css & js files!
For reference: this is the location block from my nginx.conf.default file:
location / {
root html;
index index.html index.htm;
}
I have tried adding the root in the server block, no luck