Just started happening to us also (for past month or so). 8300HD on TimeWarner in Texas.
Getting to "Failed to Record" message and also it shows red that's it's Recording, but when you go to watch the shows in the list it's missing.
I think it has something to do with watching Live-TV during scheduled recordings. I will take a took in Navigator thread if that's the proper place.
Living Room Home-Theater (Multi-Use Room):
Epson 8350 Projector (1080p @ 96") / Panasonic 850u 46" 1080p Plasma TV
Onkyo TX-sr607 AVR (7.2ch ~ HDMI) ~ Cisco 8742hdc DVR (Spectrum/TWC)
AppleTV-4 (iTunes,Plex,DMA,Vudu) ~ Simple Control HA ~ Panasonic BD60 Blu-Ray Player
Harmony 670 Remote / HTPC (Kodi/Win10-64) Media-Server / Synology DS412+ 16tb Raid-5 NAS
Polk Audio Monitor Series-II CS-2 Center & 60,40 Pairs / PSW-505 12-Inch Sub