Why is the Automation Controller UI blank or missing formatting on an RPM-based deployment?

Issue

• When visiting the Automation Controller UI, the page loads blank or without CSS, icons, or other formatting.
• The login page and other UI locations may show unstyled HTML only.
• The Controller API may remain healthy and respond normally (for example, /api/v2/ping/ returns HTTP 200) while the UI fails to render.

• Static asset requests for CSS, JavaScript, and favicon files fail in the nginx error log with permission denied (error 13):

  [error] open() "/var/lib/awx/public/static/css/main.bcabc123.css" failed (13: Permission denied), client: <client-ip>, server: _, request: "GET /static/css/main.bcabc123.css HTTP/1.1", host: "<controller-host>", referrer: "https://<controller-host>/"
  [error] open() "/var/lib/awx/public/static/js/app.<hash>.js" failed (13: Permission denied), client: <client-ip>, server: _, request: "GET /static/js/app.<hash>.js HTTP/1.1", host: "<controller-host>", referrer: "https://<controller-host>/"
  [error] open() "/var/lib/awx/public/static/assets/favicon.ico" failed (13: Permission denied), client: <client-ip>, server: _, request: "GET /static/assets/favicon.ico HTTP/1.1", host: "<controller-host>", referrer: "https://<controller-host>/"