Thanks for the detailed explanation about the strict comparison @nigel. Pushing this to the edge case, if I set the column type for the Name column in the Detailed Costs table to be “Lookup from table” where the referenced table is the Summary table, this also breaks the formula in the Summary table.
The reason one would do this is to limit the user to a unique list of values to select from in the Name column of the Detailed Costs table. This was the route I originally took when I created this template only to find that it didn’t work. The formula in the What They Paid column is the new formula as you described: [Detailed Costs].Filter(Name = thisRow.People).Cost.Sum()
Screenshot of the Name column type:
