Linking our GitHub open source team repo, FerryTime/HackTheCommute to the Heroku app fairytime gives an error.
Item could not be created:
Unknown Error. Please contact support.
A refresh of the deploy page for the app will then show GitHub as connected. All seems fine, as it lists the branches and even shows commit diffs for the releases. This is an illusion :(
If you select manual deploy for any branch, you get another error.
Item could not be created:
Not Found
Enabling automatic deployments doesn't catch pushes to GitHub.
Deployment succeeds when pushing the git repo to Heroku.
To test that this wasn't just the Heroku app, I created and tried linking the GitHub repo to Heroku app fairyferry. It gave the same errors. To check that Heroku manual deploy at least worked, I went to Heroku app hh-helptheworld and did a manual deploy using the linked open source GitHub team repo happyhousing/happyhousing. That was successful. I also tried removing and readding the GitHub repo to all above listed Heroku apps. There was no change.
The option you'll want is called "Enable local and third party Actions for this repository".