Hello @yujin seong ,
Thanks for reaching Microsoft!
I am able to replicate your issue. "membershipType" property is not shown in v1.0, only for shared channels. For other type of channels, it is working fine.
I would recommend you to raise a support case with Microsoft Graph, a Support Engineer will be able to look into this issue and assist you better. You can raise support ticket from New support request - Microsoft Entra admin center or https://admin.microsoft.com/#/support/requests.
Hope this helps.
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