Sometimes after installing the Assemble publisher add-in, AutoCAD Architecture, AutoCAD MEP, or Civil 3D fail to load the publisher. In order to solve the problem, try these steps:
1. Open AutoCAD Architecture, AutoCAD MEP , or AutoCAD Civil 3D application and run the command ASSEMBLE_ADDRIBBON. If the command shows up, you should be able to see Assemble tab in AutoCAD. If not, please proceed to step 2.
2. Run the command NETLOAD in AutoCAD application and navigate the window to "C:\ProgramData\Autodesk\ApplicationPlugins\Assemble AutoCAD 2016 to 2017 Plugin.bundle\Contents" and open "Assemble.Publisher.AutoCAD.dll" file.