After using http_substitutions_filter module, nginx ignores `Range` http header

Question

I recently try to use http_substitution_filter_module to filter and replace some content in my nginx server.
After I added the subs_filter rule, I can no longer use Range header to retrieve the part of file but the full content.

Example:
flag.txt in /var/www/html with content:

The flag is FLAG{IAMFLAGYEEAH}.

I can use curl -r 13-16 <server-address>/flag.txt to get only part of file. Output:

LAG{

But if I enabled sub_filter rule, Range header no longer works. By using same command, I get the following result:

The flag is FLAG{NOFLAGFORYOU}.

Although filter works perfectly, the full content is returned.

Here is my nginx/sites-enabled/default config (other settings is same as the default one):

location / {
    # First attempt to serve request as file, then
    # as directory, then fall back to displaying a 404.
    try_files $uri $uri/ =404;
    subs_filter_types text/plain;
    subs_filter "FLAG{\w*}" "FLAG{NOFLAGFORYOU}" ir;
}

and my nginx version is 1.14.0. The module was installed by command apt install libnginx-mod-http-subs-filter.

How should I keep Range header working and also filter the content at the same time?