The blank warehouseId in the request payload is the confirmed root cause. This means the Excel connector is successfully displaying your warehouse selection in the UI but failing to bind it to the query execution context. This is a known regression pattern in connector updates.

Escalated steps to try:

1. Clear connector credentials completely — don't just log out. Go to Windows Credential Manager (or Mac Keychain) and remove all saved Databricks/Snowflake entries, then reconnect fresh.
2. Check for a connector update released last Friday — since multiple users report the same start date, this is almost certainly a connector-side bug introduced in a recent release. Check your Excel add-in version and compare with the changelog.
3. Downgrade the connector if an update was applied around Friday — rolling back one version often immediately resolves this.
4. Try the ODBC/JDBC connection as a temporary workaround while the connector bug is investigated.
5. File a support ticket with your connector vendor (Databricks/Snowflake support) and include the exact warehouseId:"" payload — this is strong evidence of a connector-side regression, not a user configuration issue.

Bottom line: Since multiple users hit this simultaneously after Friday, this is almost certainly a broken connector release, not something fixable on your end beyond a version rollback. Push the vendor for a hotfix.