New or Set-MgEntitlementManagementAssignmentPolicy returns Invalid Model for any policy with reviewSettings on version 2.26 of the SDK

Describe the bug

We create and set access package assignment policies using Azure DevOps pipelines on Microsoft hosted agents. Recently the stage of the pipeline which does this has been failing.

After considerable troubleshooting of the model being passed to the API via the Set-MgEntitlementManagementAssignmentPolicy or New-MgEntitlementManagementAssignmentPolicy, we've identified that it would work consistently only when no reviewSettings were passed to the cmdlet.

If reviewSettings were passed, then Invalid Model was received, despite no changes having been made to the model and the model still being valid according to the Powershell/API reference.

We furthermore identified that the commands would accept reviewSettings when the image version of the agent was 20250209.1.0 or older, but always failed when 20250224.5.0.

Looking into the version history, one of the differences was that the version of Microsoft.Graph included in 20250224.5.0 was 2.26.1, but in 20250209.1.0 it was 2.25.0.

We've since used a task to specifically install Microsoft.Graph 2.25.0 on the agent, whatever version it runs, and the commands are consistency succeeding again. So there is an issue with these cmdlets in version 2.26.1 when reviewSettings are passed - or the accepted model has changed without this being reflected in the documentation.

Expected behavior

It should be possible to pass a reviewSettings object to either cmdlet.

The model passed is very similar to that in the example here - https://learn.microsoft.com/en-us/powershell/module/microsoft.graph.identity.governance/new-mgentitlementmanagementassignmentpolicy?view=graph-powershell-1.0#example-2-code-snippet

And we also tried the exact model in the example, with the same error results.

How to reproduce

In an ADO pipeline, in a AzurePowerShell@5 task and on a windows-latest image on a Microsoft hosted agent, try to create an access package assignment policy with Set-MgEntitlementManagementPolicy and pass in parameters including a reviewSettings object like that in the example.

It will only fail if the image version of the agent selected is 20250224.5.0 or later.

SDK Version

2.26.1

Latest version known to work for scenario above?

2.25.0

Known Workarounds

Use another AzurePowerShell@5 task to manually install version 2.25.0 of the SDK using Install-Module 'Microsoft.Graph' -Scope CurrentUser -RequiredVersion 2.25.0 -Force -AllowClobber

Debug output

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### Configuration

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### Other information

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Start by reproducing the failure in an AzurePowerShell@5 task with New-MgEntitlementManagementAssignmentPolicy or Set-MgEntitlementManagementAssignmentPolicy and a reviewSettings object. Compare Microsoft.Graph 2.25.0 with 2.26.1 using the linked documentation example; done means both cmdlets accept reviewSettings without Invalid Model errors.