Custom CSS App - Not seeing changes reflected PEBCAK?

Summary of the issue you are facing:

I have installed and enabled the extension, then added a couple of simple rules, one of which being: footer { display: none !important; } as a test, but none of my CSS changes appear to reflect. I tried logging out and back in, as well as a forced refresh, and at this point I’m not sure if I’m missed something stupidly obvious!!

The Basics

  • Nextcloud Server version (e.g., 29.x.x):
  • Operating system and version (e.g., Ubuntu 24.04)
    • Debian 13
  • Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
    • AIO
  • Are you using CloudfIare, mod_security, or similar? (Yes / No)
    • No

Apps

php occ app:list
Enabled:

  • activity: 6.0.0
  • admin_audit: 1.23.0
  • bruteforcesettings: 6.0.0
  • calendar: 6.2.2
  • circles: 33.0.0
  • cloud_federation_api: 1.17.0
  • comments: 1.23.0
  • contacts: 8.4.4
  • contactsinteraction: 1.14.1
  • dashboard: 7.13.0
  • dav: 1.36.0
  • deck: 1.17.1
  • federatedfilesharing: 1.23.0
  • federation: 1.23.0
  • files: 2.5.0
  • files_downloadlimit: 5.1.0
  • files_pdfviewer: 6.0.0
  • files_reminders: 1.6.0
  • files_sharing: 1.25.2
  • files_trashbin: 1.23.0
  • files_versions: 1.26.0
  • firstrunwizard: 6.0.0
  • logreader: 6.0.0
  • lookup_server_connector: 1.21.0
  • nextcloud-aio: 0.8.0
  • nextcloud_announcements: 5.0.0
  • notes: 4.13.1
  • notifications: 6.0.0
  • notify_push: 1.3.1
  • oauth2: 1.21.0
  • onlyoffice: 10.0.0
  • password_policy: 5.0.0
  • photos: 6.0.0
  • privacy: 5.0.0
  • profile: 1.2.0
  • provisioning_api: 1.23.0
  • recommendations: 6.0.0
  • related_resources: 4.0.0
  • serverinfo: 5.0.0
  • settings: 1.16.0
  • sharebymail: 1.23.0
  • spreed: 23.0.3
  • support: 5.0.0
  • survey_client: 5.0.0
  • systemtags: 1.23.0
  • tasks: 0.17.1
  • text: 7.0.0
  • theming: 2.8.0
  • theming_customcss: 1.20.0
  • twofactor_backupcodes: 1.22.0
  • twofactor_totp: 15.0.0
  • updatenotification: 1.23.0
  • user_status: 1.13.0
  • viewer: 6.0.0
  • weather_status: 1.13.0
  • webhook_listeners: 1.5.0
  • whiteboard: 1.5.7
  • workflowengine: 2.15.0
    Disabled:
  • app_api: 33.0.0 (installed 33.0.0)
  • encryption: 2.21.0
  • files_external: 1.25.1
  • suspicious_login: 11.0.0
  • testing: 1.23.0
  • twofactor_nextcloud_notification: 7.0.0
  • user_ldap: 1.24.0