When assigning an issue to a project using the UI, the issue is marked as "awaiting triage", and not added to any project column:
However, the REST API requires a column_id. Is there any way to add an issue to "triage" using the API?
This is important to me. Anyone from GitHub know whether it's possible? It effectively renders the project "automation rules" inaccessible from the GitHub API.
Github got back to me on that. It is indeed not available through the REST API. You can however achieve it by using the GraphQL API.