The title says it. The instructions in http://wiki.lyx.org/LyX/SyncTeX no longer works for forward search. I think the PDF command:
okular --unique "file:$$o#src:$$n $$t"
is no longer working for new TeX software.
Inverse search is workable though.
It works in my machine (openSUSE) with the following options. In LyX, Tools > Preferences > Output > General > PDF command:
Both worked for me. Hope this solves your problem.