Hi @Micah Kuan ,
As far as I know the Operations Manager (SCOM) PowerShell module is not yet supported on PowerShell Core, because it uses .NET core, which is also a reason why not all cmdlets work.
If you have any feedback regarding this, feel free to submit it over at the SCOM uservoice page over here:
https://systemcenterom.uservoice.com/forums/293064-general-operations-manager-feedback
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Best regards,
Leon