/blog redirects to domain root

Fresh install of latest version of wordpress. After installing to /blog I can access the admin panel at /blog/wp-admin. I can access the blog at /blog/index.php. I can’t however access the blog at /blog. It redirects to /
In the database in the options table I’ve changed the option_value to /blog for both ‘siteurl’ and ‘home’. I’ve tried installing and activating the plugin ‘Deactivate Canonical Redirection’.
Any help getting this to direct properly would be appreciated.

My nginx configuration looks like this:
server {
listen 80;
server_name localhost;
charset utf-8;
root /home/ubuntu/site/app;

location / {
root /home/ubuntu/site/app;
index index.php index.htm index.html;
}

# serve static files
location ~* .(jpg|jpeg|gif|css|png|js|ico|html|xml|txt) {
access_log off;
#expire max;
root /home/ubuntu/site/app;
}

## Parse all .php files
location ~ \.php$ {
fastcgi_split_path_info ^(.+\.php)(.*)$;
fastcgi_pass backend;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /home/ubuntu/site/app$fastcgi_script_name;
#include fastcgi_params;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
#fastcgi_intercept_errors on;
fastcgi_ignore_client_abort off;
fastcgi_connect_timeout 60;
fastcgi_send_timeout 180;
fastcgi_read_timeout 180;
fastcgi_buffer_size 128k;
fastcgi_buffers 4 256k;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;

}