The issue with displaying the original query in the newly created scheduled query rule

You can see the Query (as its custom) from the previous screen - instead of pressing 'link to LA', select "Rule Name"

If you really need to see it in that KQL screen you need to "know" the "System Alert ID" and Use that to query for it, this is an example:

SecurityAlert
| where SystemAlertId in("< insert your system alert ID here>") 
| project parse_json(ExtendedProperties).OriginalQuery

You can use this KQL to find the Incident ID and last AlertID and also show the KQL, you just need to insert the Incident Number in to line #2 (which you can see top left of the Sentinel screen) when you are in the Link to LA window.

SecurityIncident
| where IncidentNumber =="< Insert the Incident ID here>"
| extend Alerts = extract("\\[(.*?)\\]", 1, tostring(AlertIds))
| mv-expand AlertIds to typeof(string), Labels to typeof(string), Comments to typeof(string), AdditionalData to typeof(string)
| join kind=leftouter
(
    SecurityAlert
     | extend ProductProcessingMin = datetime_diff('minute',  ProcessingEndTime, EndTime), ingest_ = ingestion_time()
     | extend sentinelIngestionDelayinMinutes_ = datetime_diff('minute', ingestion_time(), ProcessingEndTime)
     | extend StarttoEndDelayinMinutes_ = datetime_diff('minute', EndTime, StartTime)
) on $right.SystemAlertId == $left.AlertIds
| summarize AlertCount=dcount(AlertIds),arg_max(TimeGenerated, *) by IncidentNumber
| extend sentinelIngestiontoCreated_ = datetime_diff('minute', ingest_, CreatedTime)
| extend InvestigationElapsedTime_   = datetime_diff('minute', LastModifiedTime, CreatedTime)
| summarize arg_max(TimeGenerated,*) by IncidentNumber
| project IncidentNumber, Title, StartTime, EndTime, ProcessingEndTime, TimeGenerated, ingest_, StarttoEndDelayinMinutes_, ProductProcessingMin,
        sentinelIngestionDelayinMinutes_, AlertName, FirstActivityTime, LastModifiedTime, 
        CreatedTime
        , InvestigationElapsedTime_ 
        , sentinelIngestiontoCreated_
        , Severity, Status, Comments, ProductName, ProviderName
        , AlertIds
        , OriginalQuery = parse_json(ExtendedProperties).OriginalQuery