Issue
I tried to install the GitHub integration in my Sentry organisation, I can see the Sentry app in GitHub but the integration is not installed in Sentry.
Applies To
All SaaS Organisatons.
Resolution
Uninstall the Sentry integration from the GitHub application settings - https://github.com/settings/installations
Go through the installation process again through your Sentry organisation -> Try in an incognito browser to ensure you're linking to the correct GitHub instance.