is-yank-next-word not working

[jogot]

Hi and many thanks for taking over this project!

I cannot get the is-yank-next-word working.
This is bound to C-w and is used during isearch.

I have tested this on Windows/Unix and with PyCharm 2017.2.3/CLion 2017.2.3.
I have reset to the original keymap Emacs+ to make sure I haven't messed up anything myself.

Also some of the other keys during an isearch is not working, e.g. C-y.