I have to check every few days or my PVR just randomly decides not to record a series. The show appears on the upcoming recordings list but the red record flag is crossed out. I don't see how this could be a varying signal as it decides to drop them ahead of time. There are no scheduling conflicts.
For example, today it did not record The View although I have had a series recording for years. All week it shows the same thing. The View is listed but not going to record. There is another series recording that won't be recorded this week too. Next week those two series look like they will record. Let me repeat there are no conflicts. The View is on at 9 AM and the next recording is set for 3 PM.
All of my series recordings are set to record only new shows. The View is all new shows this week. Besides, if a scheduled show is a repeat it just doesn't appear in the list of future recordings. Repeats do not appear with a crossed out record symbol.