I think ios8 is buggy really here. I also have seen a black screen on the ios client in some situations. I wouldn't care that much about it until apple releases a good ios8 version ...
AppleTV4/iPhone/iPod/iPad: HowTo find debug logs and everything else which the devs like so much: click here
HowTo setup NFS for Kodi: NFS(wiki)
HowTo configure avahi (zeroconf): Avahi_Zeroconf(wiki)
READ THE IOS FAQ!: iOS FAQ(wiki)