NGINX sub_filter problem

I'm currently setting up a reverse proxy using nginx ...

Have it working publishing my site as a full server, but want to run it as an application.

Working config file:
server {
listen 8080;
server site.home.local;
location / {
proxy_pass https://1.2.3.4/;
}
}

Not working config file:
server {
listen 8080;
server site.home.local;
location /test/ {
proxy_set_header Accept-Encoding "";
proxy_pass http://a.b.c.d/;
gunzip on;
sub_filter_types *;
sub_filter "home" "test/home";
sub_filter "scada-main" "test/scada-main";
sub_filter "scada-vis" "test/scada-vis";
sub_filter "scada/" "test/scada/";
sub_filter "scada/resources" "test/scada/resources";
sub_filter "scada/vis" "test/scada/vis";
sub_filter_once off;
}
}

Developer mode shows that CSS and JS gzipped files are not getting their paths updated and possibly a few other problems .

We need you to use your NGINX expertise to make sure the contents of the CSS file are also being modified by the filter.