Root Cause: Newly created Action of Action Pack in Action Builder plugin not creating links if a link of action is already registered in PACKAGES/ACTION folder.
Update to a fix version listed below or a newer version if available.
Fix Status: Released
Action Builder 3.0.0 - Available
Action Builder 2.0.2 - Available
Create the links manually in these folders. Only then the new action is visible in Action Builder and in Process Assembly.