The elite banner does not resurrects people who are down. I don't know how to replicate this bug, sometimes it happens sometimes it does not. This is what I do:
- Players go down, then I use the banner on them, but they do not get resurrected. It has happened to me for a very long time, perhaps 2 years or more when doing dungeons and fractals, and the bug appears to be random so i don't know what could be causing it.