Cyclic reference error in recursive Dataflow function

(Source as table) =>
let
  //Create a list from a Not Applicable table and buffer it - List not native to Dataflow / Datamart?
  #"NA" = List.Buffer(#"Not Applicable"[#"N/A Text"]),
  //Get a count of the number of rows in the list, for recursion
  CountNA = List.Count(#"NA"),
  //Buffer the source table - not sure this is strictly required, as we actually only use it for the first recursion
  bSource = Table.Buffer(Source),
  //Get a list of the column names for the Source table - it's this list we'll scan across for Replacer function
  Columns = Table.ColumnNames(bSource),

  ReplaceWithNull = (t as table, n as number) =>
    let
      //Replace each occurence of Not Applicable text in all columns of Source
      Replace = Table.ReplaceValue(t, #"NA"{n}, null, Replacer.ReplaceValue, Columns),
      //Keep a count of the recursion; exit once we've cycled through all the Not Applicable list
      Checking = if n = CountNA-1 then Replace else @ReplaceWithNull(Replace, n+1)
    in
      Checking,
  //Finally, actually call the recursion, starting from n=0
  Replace = ReplaceWithNull(bSource, 0)
in
  Replace