It also doesn't work for me. I find the features listed below to stop working randomly. They do not work, not only in Safari, but the entire OS.
I've tried to find a solution to this problem and things like: ' killall Dock ' or disabling all Safari extensions had no result at all. The only thing that works is restarting the Mac (which is a pain in the ***) or wait for the gestures to miraculously come back on. Apart from the trackpadgestures problem, I, among many others, am experiencing UI lag when for example I'am pressing F3 to switch between apps. This problem can only be solved if you activate the "increase contrast" mode, which looks awful. Again, no update or official answer from Apple to this problem.
To me it seems like this a OS problem, that a lot of people are facing, to which Apple turns it back. From my point of view, it all began when Apple decided to release a new version of OS every year.
The funny thing is that when I went to "iStyle", the main retailer for Apple products in my country, I've seen the same issues on the Macbooks that were exposed over there, which is funny and sad at the same time.
My configuration:
Machine: 15" MBPr Late 2013 16GB RAM, 256 SSD, i7 2.0 GHz
OS: Yosemite 10.10.3