So I have been on the PTR a lot and raid tested every boss. And on every boss i have used Nature's Vigil as resto. But i still can't seem to get the stupid thing to actually heal people. Is it not supposed to make every heal also heal for 25% more to a different player? Do HoT not proc it? I have tried using regrowth, healing touch, and nourish during it's uptime and it also doesn't proc the heal. Sometimes i will see a 100-200k heal from it on a longer fight but i don't know what healed it or when.
It's very possible that it isn't working properly on the PTR, after all they are testing it. From what I understand, it should proc from all single target healing, including hots (rejuv, lifebloom and regrowth hots included) as well as regrowth, healing touch, swiftmend and nourish. I haven't played on the PTR much at all though, so I'm not a whole lot of help.