Troubleshooting

Start from the Message row and its Failure Reason. Do not rerun a flow to test a fix before checking what the last run already wrote: every run, manual or dry, writes rows.

Symptom	Check	Recovery and confirmation
Failed: Person not found in Tooling mirror: rec…	The person’s Identity Binding and Slack Tool Account in Tooling and Access	Bind the person to a human Slack account; the next scheduled run should show a Sent row for that recipient
Failed: invalid_arguments	Whether opening the DM failed first (user_not_found)	Fix the account or workspace the recipient resolves to; the flow still posts after a DM error
Sent, but the person saw nothing	External Message Id starts with dry-run-	The run was simulated; nothing was delivered
Two digests for one person on one day	Two Membership rows for the person, or two runs	One digest per membership is expected; a second run sends again
No rows for today	The scheduled run, the schema check, or nothing due	Without n8n execution history, ask the flow maintainer; a schema mismatch stops the run before any write
Recipients (Membership) blank	Failure Reason on the same row	Recipient resolution failed before Slack; nothing was sent
Recipients (Membership Name) or Audience (Membership Name) blank	Lookup configuration	Known invalid lookup; read Recipients (Membership) instead
Messages Sent looks too high	Dry-run rows counted as Sent	Exclude dry-run- ids when counting deliveries
Last Sent on a channel looks wrong	Sent At on linked rows, dry runs included	Correct Sent At only from the tool’s own timestamp
A binding does not take effect	Is Current and Active Bindings	Fix Valid From or Valid Through; remember no flow reads bindings yet

Escalation evidence

Give the maintainer the table, the row’s Created time and timezone, Status, Failure Reason and the record id in it. Keep tokens, webhook URLs and full message bodies out of shared diagnostics. See known gaps for unresolved configuration issues.