Custom Filtering

Can you tighten this up a bit? You haven't given us the raw data. You have given us an intermediate step that isn't working and explained that is is broken. 

As far as your SelectRows function, it works fine here - not sure it is the results you want, but it functionally works and you can see it in the last statement.

    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("ldG9CoMwFAXgV5HMgrk/mphNLAVLh1JKF+lQOglSly59+ybRgLEOOiTkQDjfjbatqDQXJFLBGWYIiTYkbUqmdRn67vVNwB7v3dA/P93w9qm+Nremrs72GO6DeKTzPuX6AA3qv3qVMpUb610MpeiJGiRL3wnsDTAAYyafpYEifgBGAsaCUnY7MbErUXoygPN1I8ozgyKDFob7CGFwVXrjCFAU+wyODF4YpTfGwbX0xsEaap+RR0YeG9rNHwbXsG7kRtKKgYRbFXc91Gr71x8/", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Incident ID" = _t, TIMESTAMP = _t, #"Start Time" = _t, Duration = _t, Policy = _t, Violation = _t, SEVERITY = _t, Index0 = _t, Prev.INCIDENT_ID = _t, Index1 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"TIMESTAMP", type datetime}, {"Start Time", type datetime}, {"Duration", Int64.Type}}),
    #"Filtered Rows" = Table.SelectRows(#"Changed Type", each ([Duration]<> null and [Duration] <> "" or ([Incident ID] = [Prev.INCIDENT_ID])))
in
    #"Filtered Rows"

How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.

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