Recently I found an issue regarding shelf tool in Houdini, Since I am working in studio, I need to get access to the server. You need to setup custom variable to make it works properly.
Therefore I put this line.
HOUDINI_ACCESS_METHOD = 2
But then new problem comes up. Whenever I try to create the new shelf tool. Houdini can't define shelf definition.
The solution is you need to copy ShelfDefinitions.shelf from
"C:\Program Files\Side Effects Software\Houdini xxx\houdini\toolbar\ShelfDefinitions.shelf "
to "C:\Users\USERNAME\Documents\houdini xx\toolbar"
That's it .