The tag key is seen within the 'tag' column within asset reporting, however the tag is not appearing in the perspective editor.
Tag keys are required to be enabled via the 'Tag Management' tool (Governance > Tag Management) before being available in many areas of the platform.
Please review the tag keys listed in the tool:
If a key is not enabled, this can be done on a key by key basis or in bulk.
For more information regarding tag management, please see: https://techdocs.broadcom.com/us/en/vmware-tanzu/cloudhealth/tanzu-cloudhealth/saas/tnz-cloudhealth/using-and-managing-tanzu-cloudhealth-tag-management.html