Identity Provider Mapper: Username Template Importer - Missing ${ALIAS} when 'uppercase' applied to NameID

In an Identity Provider’s Mapper – I have a mapper with ‘Username Template Importer’ + ‘Target=LOCAL’ (with sync over-ride as ‘force’) – the template is ‘${NAMEID | uppercase}@${ALIAS}’.

However, the ‘${ALIAS}’ is not appearing in the Keycloak account’s username (new account after the above was applied). The Alias appears if the ‘uppercase’ condition is removed:’’${NAMEID @${ALIAS}’.

Have I missed something obvious?