Create a VDB
Create a source model by importing from JDBC
Add model to VDB
Define data role with a table wide condition like "USERNAME=substring(user(), 1, locate('@', user()) - 1)"
Synchronize, save VBD.
Condition is applied to queries, can be seen in the designer, can be seen in the VBD internal xml.
Keep working and after another save (not necessarily de second one) condition field value is empty in designer and gone from teh XML as well.

This has happened more than once and to more than one developer in the team.