Different results from Invoke-WebRequest and Invoke-RestMethod - powershell

Question

I am trying to call Azure Rest API and get Schedules of DevTestLabs. I tried Invoke-RestMethod, but it doesn't give value on "dailyRecurrence" key. But Invoke-WebRequest does.
What would be the reason for that?
URL
$url = "https://management.azure.com/subscriptions/{subscriptionID}/resourceGroups/{resourseGroup}/providers/Microsoft.DevTestLab/labs/{LabName}/schedules/LabVmsShutdown?api-version=2018-10-15-preview"
URL with $expand
$url = "https://management.azure.com/subscriptions/{subscriptionID}/resourceGroups/{resourseGroup}/providers/Microsoft.DevTestLab/labs/{LabName}/schedules/LabVmsShutdown?$expand=properties(dailyRecurrence)&api-version=2018-10-15-preview"
Calling Invoke-RestMethod
$output = Invoke-RestMethod -Uri $url -Method "GET" -ContentType "application/json" -Headers $authHeaders
properties : #{status=Enabled; taskType=LabVmsShutdownTask; dailyRecurrence=; timeZoneId=AUS Eastern Standard Time;
notificationSettings=; createdDate=26/03/2019 4:38:18 PM; provisioningState=Succeeded;
uniqueIdentifier=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX}
Calling Invoke-WebRequest
$output = Invoke-WebRequest -Uri $url -Method "GET" -Headers $authHeaders
Content : {"properties":{"status":"Enabled","taskType":"LabVmsShutdownTask","dailyRecurrence":{"time":"1900"}
,"timeZoneId":"AUS Eastern Standard Time","notificationSettings":{"status":"Disabled","timeInMinute
s":30},"createdDate":"2019-03-26T03:38:18.0726376+00:00","provisioningState":"Succeeded","uniqueIde
ntifier":"XXXXXXXXXXXXXXXXXXXXXXXXX"},"id":"/subscriptions/XXXXXXXXXXXXXXXXXXX/resourcegroups/XXXXXXXXXXXXX/providers/microsoft.devtestlab/labs/XXXXXXXX/schedules/labvmsshutdown","name":"LabVmsShutdown","type":"microsoft.devtestlab/labs/schedules","location":"australiasoutheast"}

Answer 1

The problem:
is merely a display problem,
albeit one that exposes a long-standing bug, still present as of PowerShell Core 7.2.0-rc.1, namely that [pscustomobject] instances mistakenly stringify to the empty string - see GitHub issue #6163.
In short:
The data is there in the Invoke-RestMethod output, it just appears to be missing - see the next section.
Use $output.properties.dailyRecurrence to see it or, to more helpfully visualize the output, use it $output | ConvertTo-Json to re-convert it to (prettified) JSON.
Note: Situationally, you may have to add a -Depth argument to fully represent object graphs with a depth greater than 2 - see this post.
Invoke-RestMethod - unlike Invoke-WebRequest - has deserialization built in: with a JSON response, it automatically parses the JSON text returned into a [pscustomobject] graph as if ConvertFrom-Json had been applied to it.
You're seeing the default formatting of the resulting object graph, which isn't really suited to visualizing nested [pscustomobject] instances, which are represented by their .ToString() values - and therefore - due to the bug - may appear to have no value, even when they do.
By contrast, since the output from Invoke-WebRequest reports the JSON text as-is in the .Content property of its output objects, the problem doesn't surface there.
A simple demonstration of the bug:
[pscustomobject] #{
nested =
[pscustomobject] #{
deep =
[pscustomobject] #{
deepest = 'down'
}
}
}
As of PowerShell Core 7.2.0-rc.1, this yields the following, mistakenly suggesting that .nested.deep has no value, even though it clearly does:
nested
------
#{deep=}