anybody else seen a bulb suddenly fail.. it is on the hue bridge directly and keeps dropping off (unreacheable) i power cycle it and it works for awhile.. nothing has changed with the hue network for a couple of years.. i replaced with a spare bulb (unfort. bigger and not r19) and it is again working fine so it points to a failure in the bulb itself.
In my case it didn't suddenly fail but would do weird things like coming on the wrong colour, or when I turned on a different light it would come on briefly. Then I added some more bulbs and got suspicious when they kept reporting a different colour from the one they were. In the end I changed the dodgy bulb and the whole system started working properly again. Obviously passing on faulty messages to the Hue mesh.
I haven't seen that particular kind of failure (sounds like it might be just Zigbee failure? Or some kind of firmware issue?), only one that totally stopped turning on at all. In my case, I was able to get it replaced under warranty, as it was just under a year old. In the US, I believe they are covered for at least 2 years, so if you suspect it's not just a network problem (maybe verify in a fixture closer to another bulb or the Bridge just in case?), then you might want to try reaching out to their support. They weren't the fastest or the absolute best (I had to pay for shipping), but the issue did get resolved for me, at least. 
