Table.FirstN function doesn't seem to work properly for my case...

HI Anonymous,

If you want to filter rows from a table based on some conditions, please use selectrows instead of FirstN/LastN functions. After I replace the function I mentioned above on your sample code, these steps work well.

Full query:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("ndQ9bsMwDAXg3acQvDYWSOrP1lWCDBocJEVbF4085PaVOrSMHaVyJi3+8J4Jiftm32K7a+M5ntPxOp0+0kFA1IHpSAlED8ZrkMoM4gUIIH/9NY/tYXdrL+GdUxDoPAxeG9kr+qXH8HZZ288QFxa9SVZLcmZtm6Qp6znOi2T7o61XyqOWtlf3kpnlybZDJzD9be9pkI7wfrLKOsSwTkaB9Di5bAut/0bN6BOlddZTnBbBQ03pgu0rSjPKS7v/Sxdjq+Zcts9Wrpyzyfoar9uvZdY26zGOy6foKp6iLdgUXbBsXiVcswOY3bwDmN20A5rDNw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Id = _t, Ref = _t, User = _t, Creationdate = _t, Isuserpartofteama = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Id", Int64.Type}, {"Ref", type text}, {"User", type text}, {"Creationdate", type datetimezone}, {"Isuserpartofteama", type logical}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", (k)=> Table.SelectRows(#"Changed Type",each [Id]=k[Id])),
    #"Removed Duplicates" = Table.Distinct(#"Added Custom", {"Id"}),
    #"Removed Columns" = Table.RemoveColumns(#"Removed Duplicates",{"Ref", "User", "Creationdate", "Isuserpartofteama"}),
    Custom1 = Table.SelectRows(#"Removed Columns", each Table.Contains([Custom], [Isuserpartofteama = true])),
    #"Added JobStarted" = Table.AddColumn(Custom1, "JobStarted", each Table.First(Table.SelectRows([Custom], each [Isuserpartofteama] = true))[Creationdate], type datetimezone),
    #"Added JobEnded" = Table.AddColumn(#"Added JobStarted", "JobEnded", each Table.Last(Table.SelectRows([Custom], each [Isuserpartofteama] = false))[Creationdate], type datetimezone),
    #"Added TimeTaken" = Table.AddColumn(#"Added JobEnded", "TimeTaken", each [JobEnded] - [JobStarted], type duration),
    DebugJobEndedFirstStep = Table.AddColumn(#"Added TimeTaken", "DebugJobEndedFirstStep", each Table.First(Table.SelectRows([Custom], each [Isuserpartofteama] = false))[Creationdate], type datetimezone)
in
    DebugJobEndedFirstStep

Regards,

Xiaoxin Sheng