Category slugs starting with numbers return 404 in a subfolder install

Any category with a slug that starts with a number returns a 404 if visited directly, but works find if navigating there from the homepage. If relevant, this is a discourse instance nested in a subdirectory /forum. => doesn’t work

Hack Overflow => click on Graduate Projects => works

Here is the relevant parts of my app.yml

- replace:
     global: true
     filename: /etc/nginx/conf.d/discourse.conf
     from: proxy_pass http://discourse;
     to: |
        rewrite ^\/(.*)$ /forum/$1 break;
        proxy_pass http://discourse;
  - replace:
     filename: /etc/nginx/conf.d/discourse.conf
     from: etag off;
     to: |
        etag off;
        location /forum {
           rewrite ^\/forum\/?(.*)$ /$1;

Any thoughts? Might this be related to Slugs that start with numbers parsed as IDs?

The easiest workaround is to avoid leading numbers in your categories.