This happens sporadically and has been happening ever since we got the box 1.5 years ago. It isn't often, but it is often enough to be an irratant. It has definitely been rebooted a few times but maybe periodic reboots might do the trick. I'll start doing so once a week and see if it helps.
I have an SA8300 and sometimes something does not record for no explicable reason. It was set to record The Mentalist at 9 and The Good Wife at 10 on CBS. I watched The Good Wife when it was still recording, skipping through the commercials and then went to bed. Today I'm looking for The Mentalist and it's not there! (I didn't actually notice if it was recording last night because the dark red RECORD display is hard to see from across the room.) I see it's in my scheduled recordings from 10:01-11:00, but on Zap2it the time is 10:00-11:00. I can't see it on the Rogers IPG because it only lets you look back 2 hours, but I bet it was 10:00-11:00. That one minute difference in start time makes all the difference because it seems that the PVR will not recognize any show it's supposed to record if the scheduled time doesn't precisely match the listed time. A few months ago I never saw this, but now a lot of shows originating with CBS have start and/or end times one minute off. Unfortunately, it's not consistent, so if you originally schedule a show that's 10:01-11:00 and it changes to 10:00-11:00, it won't record. It really annoys me that some networks have gone to these oddball times and then not staying consistent.
One workaround would be to set shows to record "on this channel any time", but that can get annoying if there are many repeats during the week. I haven't tried "First Run only on this channel", maybe that may work also, but I've seen people report that they've missed shows doing that.
Well, it did it to me again. I had set the PVR to record Bones on Global at 8 and The Blacklist at 10. Bones recorded, but The Blacklist didn't because it actually started at 10:01, not 10:00 as it was when I scheduled the series. Worse still, Global doesn't timeshift this program;; it's on at the same time in Calgary and BC as in Ontario, so I've missed it unless I can find it on line. (AAMOF, I think I missed the previous TWO episodes for this same reason.) This is totally unacceptable! If the networks keep **bleep** with the start times, then at least Rogers should accommodate this.