support "Managment Groups" Scope under CSP Cost Management.
Currently it is not supported selecting a "Management Group" Scope it there are CSP subscriptions (which is currently supported with Azure Plan).
Axel Andersen commented
Customers use Cost Management for all their subscriptions. When they are set up in a Enterprise Scale management group design, they can have different subscription types nested in the management group tree. The customer expects the experience of Cost Management to show all subscriptions even though they "only" show the pay-as-you-go price.
It is a lot easier to explain to the customer, that the CSP subscriptions in the mix only show the Pay-As-You-Go price the explaining that the functionality in the portal works less well with CSP subscriptions.
When asking the customer to use a custom portal for cost management, they are often discuoraged to use CSP, because they only want to use a single portal for cost management