Adding a tag using the environment variable SPT_XCMETRICS_TAG doesn't have any effect. When querying the database the tag comes back empty. I know I set it correctly in the client because I saw the line Started appending a tag "SomeTag" being printed to the Console.
The same is true for some of the fields in build/host/:id endpoint

I strongly suspect it has something to do with the AddMetadataEffectHandler.