Fix the action around Formula.Firewall so instead of a weird error you get prompted with something actionable
PowerQuery throws this odd error in some cases when a query references another query. Instead of the error, it should prompt you to select the correct privacy setting.
Formula.Firewall without Ignoring Privacy Levels? Query 'x' (step 'Source') references other queries or steps and so may not directly access a data source. Please rebuild this data combination
Questions on this come up repeatedly in the forums. See two discussions here:https://social.technet.microsoft.com/Forums/en-US/ee1381f7-c919-4134-be96-5f06dbdb9cd5/how-to-fix-formulafirewall-without-ignoring-privacy-levels-query-x-step-source-references?forum=powerquery