~/.config/github-copilot/apps.json not created/saved even though authentication succeeds

I've been successfully using copilot.vim 1.59.0 in Neovim 0.12.2 on Ubuntu 22.04.5 with a corporate Github Copilot subscription; I can verify that authentication succeeds and that completions are successfully processed when I edit code (and if I examine the copilot.vim log). Recently, however, it seems that the plugin isn't saving the authentication token into apps.json. This poses issues with another vim plugin that relies upon copilot.vim for authentication (https://github.com/olimorris/codecompanion.nvim). Any thoughts as to what could be preventing the apps.json file from being created/saved? The ~/.config/github-copilot/ folder appears to be writable, i.e., I can manually save files there. Tried deleting the whole directory before starting Neovim and authenticating; after authentication, the directory was recreated; it contains auth.db, auth.db-shm, auth.db-wal, versions.json, but not apps.json