Time Span between 2 rows with conditions

Your sample data doesn't seem to match your explanation.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WsrAyMVXSUfLPAxKhBUqxOmAhMyAvKDUxpRJF1BLIC84oLVFwyS8HqQdTEDlTQ7CO4pLEohI0GWMg3zG5JLMsFdkwU3OQhtK8vMy8dIS4pZWBAZDnl1+iALMebhRQzhCXA4ByRtgdYGllaIDmP6CQKab/LK2MQMb7p6XBtccCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Time = _t, Tag = _t, #"System Status" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Time", type time}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"System Status"}, {{"Time", each List.Min([Time]), type nullable time}},GroupKind.Local)
in
    #"Grouped Rows"

Use Grouping with GroupKind.Local