Expression Error when Pivot Column (no value aggregation)

try this code to see if overcomes your problem (I hypothesized that the two tables you published are the starting one and the expected one)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WSipT0gERsTq42cmGQHaqIYRtBGQXGCGJG2GI4zUnH4s5xOgFqzFGshfIjgUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Added Index" = Table.AddIndexColumn(Source, "Index", 1, 1),
    #"Duplicated Column" = Table.DuplicateColumn(#"Added Index", "Column1", "Column1 - Copy"),
    #"Pivoted Column" = Table.Pivot(#"Duplicated Column", List.Distinct(#"Duplicated Column"[Column1]), "Column1", "Column1 - Copy"),
    #"Sorted Rows" = Table.Sort(#"Pivoted Column",{{"Index", Order.Ascending}})
in
    #"Sorted Rows"

if you don't need index, use this

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WSipT0gERsTq42cmGQHaqIYRtBGQXGCGJG2GI4zUnH4s5xOgFqzFGshfIjgUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Duplicated Column" = Table.DuplicateColumn(Source, "Column1", "Column1 - Copy"),
    #"Pivoted Column" = Table.Pivot(#"Duplicated Column", List.Distinct(#"Duplicated Column"[Column1]), "Column1", "Column1 - Copy",each _),
    #"Expanded bv" = Table.ExpandListColumn(#"Pivoted Column", "bv"),
    #"Expanded c1" = Table.ExpandListColumn(#"Expanded bv", "c1"),
    #"Expanded c2" = Table.ExpandListColumn(#"Expanded c1", "c2"),
    #"Sorted Rows" = Table.Sort(#"Expanded c2",{{"Index", Order.Ascending}})
in
    #"Sorted Rows"