You should supply the vpath, which is the path without the mountpoint path, to TeamSite command line tools; for this example it would be:
iwextattr -g TeamSite/Templating/DCR/Type /default/main/WORKAREA/templatedata/TravelAdvisory/Advisory/data/NorthAmerica/test_advisory
We have this working with the complete path in production. So I do not believe a code change is necessary, should be a configuration in the server