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 $$t"
is no longer working for new TeX software.
Inverse search is workable though.
It works in my machine (openSUSE) with the following options.
PDF command under
okular --unique "file:$$o#src:$$n $$f"
okular --unique "$$o#src:$$n $$f"
Both worked for me. Hope this solves your problem.
$$f option only works with LyX 2.0.5+.