Not recording

I have called Cox for the past 5 nights and spending many hours. My DVR is not recording programs.  They appear with the red circles in the guide but the programs do not record. Yes, I have plenty of space available.  Also, I touch record to record a program I am watching, it says it is recording and then it doesn't record it.  They came out and changed the filter and that didn't help.  Anybody?  I've rebooted (many times) Cox has rebooted (many times).  Weird thing is:  the programs tape fine until 4PM then they don't record.