The issue applies to the 32 and 64 bit of the Domino Designer 12.0.2. It occurs in Forms, Views and Folders.
Also, the issue only occurs when you open an application in Designer from the Notes workspace.
When you open an application in Domino Designer and edit i. e. a view, you expect a list of (default) agents and also a list of available objects as shown in the following image.
When you open the application in Domino Designer from the Notes Workspace, you will see this
I have found the trigger. It is related to the width of the tab navigation. I have a Marvel client configuration for it, which sets the value of the Workspace_Navigator_Width variable to 55. With this, only the colored squares are visible.
If one now opens an application in the designer via the right mouse button, the objects and agents are only visible as symbols. If you change the width (at runtime), the objects and agents become visible again.
Here is a short video demoing the issue.
HCL support was able to reproduce. the issue is being tracked under SPR# ASHECLEFDF