Mutiple classified/Trusted data error when appending two tables

Hi All. 

I've run into an error when I append two queries/tables in PowerQuery: 

It's worth noting the two tables/queries I'm appending have a custom function. I'm using the function so the query can iterate through a list of excel paths and sheets. 

Query 1: 

let
    Source = Excel.Workbook(File.Contents("C:\Users\Sabastian.Chetty\Desktop\Paths - M code - Finance Reports.xlsx"), null, true),

    fnSMU_Sheet = Source{[Item="fnSMU",Kind="Sheet"]}[Data],

    //Cleaning Starts Here:
    PromotedHeaders = Table.PromoteHeaders(fnSMU_Sheet, [PromoteAllScalars=true]),

    InvokedCustomFunction = Table.AddColumn(PromotedHeaders, "SMU_Excel_File_Cleaner", each SMU_Excel_File_Cleaner([Paths], [Sheet Name])),

    ExpandedSMU = Table.ExpandTableColumn(InvokedCustomFunction, "SMU_Excel_File_Cleaner", {"Parent Category", "Cost Category", "Month", "Value", "Department", "Management Unit"}, {"SMU_Excel_File_Cleaner.Parent Category", "SMU_Excel_File_Cleaner.Cost Category", "SMU_Excel_File_Cleaner.Month", "SMU_Excel_File_Cleaner.Value", "SMU_Excel_File_Cleaner.Department", "SMU_Excel_File_Cleaner.Management Unit"})
in
    ExpandedSMU

Query 2: 

let
    Source = Excel.Workbook(File.Contents("C:\Users\Sabastian.Chetty\Desktop\Paths - M code - Finance Reports.xlsx"), null, true),

    fnAMU_Sheet = Source{[Item="fnAMU",Kind="Sheet"]}[Data],

    // Cleaning Starts Here:
    PromotedHeaders = Table.PromoteHeaders(fnAMU_Sheet, [PromoteAllScalars=true]),

    InvokedCustomFunction = Table.AddColumn(PromotedHeaders, "AMU_Excel_File_Cleaner", each AMU_Excel_File_Cleaner([Paths], [Sheet Name])),
    
    ExpandedAMU = Table.ExpandTableColumn(InvokedCustomFunction, "AMU_Excel_File_Cleaner", {"Parent Category", "Cost Category", "Month", "Value", "Department", "Management Unit"}, {"AMU_Excel_File_Cleaner.Parent Category", "AMU_Excel_File_Cleaner.Cost Category", "AMU_Excel_File_Cleaner.Month", "AMU_Excel_File_Cleaner.Value", "AMU_Excel_File_Cleaner.Department", "AMU_Excel_File_Cleaner.Management Unit"})
in
    ExpandedAMU

After running I am able to append these into a single table, I used the UI and get the following code: 

let
    Source = Table.Combine({fnSMU, fnAMU})
in
    Source

After all of these steps I get the error listed at the start of this post.

I did some digging and found that two sources may be causing the issue so I followed the steps in the following article with no luck: https://www.excelguru.ca/blog/2015/03/11/power-query-errors-please-rebuild-this-data-combination/

Any idea where I'm going wrong?