We previously came across this alert when using an Update 6 version of the Personal.ucf file in Update 10, so we've since modified the cache.ucf file to define our custom WorkSpace and WorkSet. After installing OpenBuildings Designer Update 10.1 we copied a stored version of this file to the local "C:\Users\User.Name\AppData\Local\Bentley\OpenBuildingsDesigner\10.0.0\prefs" folder and then double-clicked on a DGN file to launch OpenBuildings Designer for the first time. But when the application opens the cache.ucf file is overwritten with a “No WorkSet” version, resulting in that same "No Workset Alert, associated Workset not found" message. This will continue until OpenBuildings Designer is launched from a desktop shortcut and our custom WorkSpace and WorkSet manually selected.
It was discovered that the target location of the custom WorkSpace during startup was pointing to C:\Program Data\Custom_Workspace\Bentley instead of the correct C:\Program Data\Bentley\Custom_Workspace folder. This was traced back to "_USTN_CUSTOM_CONFIGURATION=C:\Program Data\Custom_Workspace\Bentley\" being defined in the ConfigurationSetup.cfg file:
Since this variable is left blank by default, the folder name was removed leaving it as "_USTN_CUSTOM_CONFIGURATION=":
Once this was changed, double-clicking on any DGN file launched OpenBuildings Designer Update 10.1 for the first time with the Custom WorkSpace and WorkSet as defined in the template cache.ufc file.