Sebastien Tee

I had the same problem appearing after installing RM23, even after deleting everything related to it, my shelf was not saved on Houdini's exit like before.

The way I got around it is:

Go to the small arrow in the right to corner of the shelf and select “Save Shelf set As”
Save it to like myshelf.shelf then replace the default.shelf in /toolbar in your Houdini 18 pref directory.

Cheers.