I just installed MiKTeX and LyX on my new Apple laptop (yosemite 10.10).
When I open an old
.lyx file or create a new one the eyes icon on the top left (
cmd R) for creating a PDF is inactive, as well as the for other icons on the right. If I click in the documents settings on "use non TeX fonts" then the eyes are active.
One users on this group said he solved this problem by deleting the directory
.../Libaray/Application Support/Lyx.../ and restarting LyX
Unfortunately, I am not an expert and I can't find this directory.