Google AI Studio GitHub sync fails even after revoking and reinstalling GitHub App permissions

Google AI Studio GitHub sync is failing for me even after completely revoking and reinstalling the GitHub App.

Error shown in AI Studio:

Failed to load file differences, The GitHub repository could not be found, or you lack permissions. Please ensure the AI Studio GitHub App is installed.

I have already revoked the AI Studio GitHub App, reinstalled it, reconfigured permissions, tried all repositories access, selected repository access, confirmed the repo is included, logged out/in, refreshed, and repeated the whole flow several times.

I also tested it on Safari, Brave, and private/incognito windows in both browsers.

The GitHub App appears to be installed correctly and has access to the repository, but AI Studio still cannot load the file differences.

Is this a known Google AI Studio GitHub integration issue? Is there any backend cache/reset or workaround needed?