Added attachments don't appear in existing site

Situation: We have an existing site, consuming an existing map service. In the database, we enable and load attachments into a feture class that is data source for one of the map service layers. Then, republishes and overwrites the map service.

Experience: The attachments don't appear in the features attribute table. You have to re-add the map service to the site to make that happen.

Is this an expected behavour of the Essentials system, or could it be a bug?

Jostein