I just installed Yosemite 10.10.5 on my imac27 and I ran LYX. I can view the compiled pdf file using cmd+T as usual. Problem is: each time I modify the file and want to see the result on the pdf, the command cmd+T return to document to the first page, instead of staying on the same page. It is very much annoying and make LYX very uncomfortable, I would like preview staying at the same page. After having that problem, I installed the last version of LYX (2.1.5), and of mactex-2015, but nothing changed. Any idea would be greatly appreciated.