This issue is often found when the user tries to place a cell from the ‘Cell Library’ list. In some cases, it is often found when trying to open the Cell Library dialog then while clicking on the arrow just beside the Cell,and also after clicking the ‘Browse Cell’ box in the Place Active Cell dialog, for both cases, Cell Library does not load.
To solve this issue please follow the steps below,
1. Go to this folder location belowC:\Users\username\AppData\Local\Bentley\OpenBuildingsDesigner
2. Delete or rename the file called 10.0.0