Within the CloudHealth platform Azure Reservation Orders will sometimes sit within a Subscription labelled "Other".
This is expected behaviour when a Reader Role hasn't been deployed to the Reservation Order within the platform, as the CloudHealth platform will be deriving the Reservation Order. The CloudHealth platform determines the Subscription a Reservation Order should be billed under based on the Billing Scope ID field.
This field can only be pulled in if the platform has accessed via a Service Principal to collect metadata for the Reservation Order, this setup process is detailed under the following:
MCA - https://docs.vmware.com/en/VMware-Tanzu-CloudHealth/SaaS/getting-started-with-vmware-tanzu-cloudhealth/GUID-azure-quick-start.html#step-6--assign-a-reader-role-to-azure-reservation-orders-25
CSP - https://docs.vmware.com/en/VMware-Tanzu-CloudHealth/SaaS/working-with-partner-platform-vmware-tanzu-cloudhealth/GUID-azure-managed-service-provider.html#step-5-assign-a-reader-role-to-azure-reservation-orders-9
EA - https://docs.vmware.com/en/VMware-Tanzu-CloudHealth/SaaS/getting-started-with-vmware-tanzu-cloudhealth/GUID-azure-quick-start.html#step-7--assign-a-reader-role-to-azure-reservation-orders-9
PAYG - https://docs.vmware.com/en/VMware-Tanzu-CloudHealth/SaaS/getting-started-with-vmware-tanzu-cloudhealth/GUID-azure-quick-start.html#step-4--assign-a-reader-role-to-azure-reservation-orders-16
Once the Reader Role has been deployed to the Reservation Order and metadata has been collected for the Reservation Order the Cost for the Reservation Order will appear against the Subscription detailed under the Billing Scope ID field.