One of the reasons AWS Tags are not showing in the platform can be if the Direct Service falls in the 'Basic Cost Allocation' level.
For Level: Basic Cost Allocation - Tags are supported using AWS Cost Allocation tags within the Cost and Usage Report (CUR). This means the platform will pull associated tags via the bill, not the API. As long as the bill contains the tags, then the platform should be importing the tags into the platform. Here is a list of services supported at this level:
Follow these steps for the best way to have tags appear as expected:
For more information regarding account configuration, see: https://docs.vmware.com/en/VMware-Aria-Cost/SaaS/getting-started-with-vmware-aria-cost/GUID-aws-quick-start.html?hWord=N4IghgNiBc4O4GcAEBjA9gOwGYEsDmArgE5gAuOmIAvkA