It is stated that in the initial release of “Work” only public pages can be accessible, and pages which requires authentication can’t be accessible till next update.
Agent Mode has now been officially marked as unavailable, so this was apparently not just a temporary UI issue.
The bigger problem is that Work, Deep Research, Codex, and Computer Use do not reproduce the same virtual-computer + visual-browser workflow Agent Mode provided. There is currently no real replacement for that capability.
I opened a dedicated feature request asking for Agent Mode, or a true functional equivalent, to be restored:
Title: Agent Mode was removed with no real replacement
ID: 1389601
For the time being, you can have the same capability if you use the Desktop App and it has access through your Chrome browser for both authenticated sessions and public pages,etc. If you are using Linux, then you can download using GitHub - ilysenko/codex-desktop-linux: Unofficial ChatGPT desktop app for Linux (formerly the Codex app), built locally from OpenAI’s official macOS app. Includes Chat, Work, and Codex. Packages for Debian/Ubuntu (.deb), Fedora/openSUSE (.rpm), Arch (pacman), Nix/NixOS, and AppImage, with Wayland and X11 support. · GitHub