Stack Overflow Error Appending

After trying to append two queries together I receive the stack overflow error, the data isn't too large and I've actually performed the same sequence with other very similar data from Azure. I cannot share the data as it is confidential, however please see below the queries: 

let
    Source = AzureDataExplorer.Contents("yyyyyyyyyyyyyyyyyyyyy", "xxxxxxxxxx", "    let stime = datetime(2020-07-16 00:00:00);#(lf)    let etime = datetime(2020-07-16 23:00:00);#(lf)    Common2#(lf)    | where SiteId ==('yyyy')#(lf)    | where TS between (stime..etime)#(lf)    | where Tag == 'xxxxxxxxxx'#(lf)    |sort by TS asc#(lf)    |serialize TS#(lf)    |extend Value = tolong(Value)#(lf)    |extend newsession=iff(isnull(prev(Value)) or ((Value) <= 250 and prev(Value) > 250), 1, 0)#(lf)    |extend session_id = row_cumsum(newsession) ", [MaxRows=null, MaxSize=null, NoTruncate=null, AdditionalSetStatements=null]),
    #"Appended Query" = Table.Combine({Source, Query3}),
    #"Added Conditional Column" = Table.AddColumn(#"Appended Query", "Main Mixer Weight", each if [Tag] = "yyyyyyyyyyyyyyyyyyyyy" then [Value] else null),
    #"Changed Type1" = Table.TransformColumnTypes(#"Added Conditional Column",{{"Main Mixer Weight", type number}}),
    #"Changed Type" = Table.TransformColumnTypes(#"Changed Type1",{{"TS", type datetime}})
in
    #"Changed Type"

and I am a query with several more columns to it with the same date and time. 

I have done this same query with more data from a similar source and have no problems with it, could anyone help?