October 2020 - Unable to Save File to Report Server

I am having a similar issue as posted about here. Using the latest version of Power BI Desktop for Report Server (2.86.1321.0) and Server (Version: 1.9.7675.15620 (Build 15.0.1104.300)) I am unable to upload or save a file which references a function that takes a parameter as a value.

Error when doing Save As from within Power BI Desktop:

Error when trying to upload the file via Chrome:

Function - Real Name Lookup:

(sharePointSite, listName)=>
let
    Source = OData.Feed("https://am-regional.internalspsite.com/sites/CRA/_api/web/lists/GetByTitle('" & listName & "')/Fields?$select=Title,InternalName", null, [Implementation="2.0"]),
    #"Replaced Value" = Table.ReplaceValue(Source,"_x002d_","-",Replacer.ReplaceText,{"InternalName"}),
    #"Replaced Value1" = Table.ReplaceValue(#"Replaced Value","_x0020_"," ",Replacer.ReplaceText,{"InternalName"}),
    recs = Table.ToRecords(#"Replaced Value1"),
    lsts = List.Transform(recs, each Record.ToList(_))
in
    lsts

Query - High Level Business Line:

let
    Source = SharePoint.Tables("https://am-regional.internalspsite.com/sites/CRA/", [ApiVersion = 15]),
    #"2cc193b4-d0e8-4ee2-ae77-a0f03817d347" = Source{[Id="2cc193b4-d0e8-4ee2-ae77-a0f03817d347"]}[Items],
    #"Renamed Columns" = Table.RenameColumns(#"2cc193b4-d0e8-4ee2-ae77-a0f03817d347",{{"ID", "ID.1"}}),
    #"Renamed Fields"=Table.RenameColumns(#"Renamed Columns", #"Real Name Lookup"("https://am-regional.internalspsite.com/sites/CRA/","High Level Business Line"), MissingField.Ignore) 
in
    #"Renamed Fields"

As soon as I remove the listName parameter from the function call in the OData.Feed, and hard code it with a string value like so:

Source = OData.Feed("https://am-regional.internalspsite.com/sites/CRA/_api/web/lists/GetByTitle('High Level Business Line')/Fields?$select=Title,InternalName", null, [Implementation="2.0"]),

the file will upload and save just fine.

So it appears there is some kind of an issue with making use of paramters right now in certain contexts?