In a very specific situation where multiple versions of OpenBuildings Designer are used on a project it is possible for the contents of an existing Structural.rul to be deleted.
We have identified a bug in Update 4 and subsequent versions where a check for read-only status was missing for the structural rules file.
In the context of system testing or troubleshooting this results in an open DGN file as read-only operation carried out by an administrator privileged user with an OpenBuildings Designer version newer than the version, thereby updating the structural rules file with a new version number and also rewriting the active content.
The next time a DGN file is opened with the earlier version of OpenBuildings Designer it is unable to read the updated file (our dataset content is not backwards compatible) and the rules are not available to users.
The next time it is opened by an administrator privileged user with the earlier version the file content is lost during the rewrite.
This scenario can be avoided by always using a single version of OpenBuildings Designer on a given project so that the structural drawing file is always accessed by the same version.