Remote loses some programming functionality after a few minutes

I was using a new Comcast XR11 remote on my Visio TV for 6 months with no issues.  Recently the on/off and volume commands stopped working.  I reprogrammed the remote and this functionality started working again.  However, after a few minutes the volume and power commands no longer worked.  All other remote functionality was fine.  I reprogrammed it many times, trying all the codes, but nothing resolved it.  I spoke to Comcast customer service and they suggested a new remote.  They initially sent the XR2 remote by mistake.  That had the same issue.  I then got a replacement XR11 remote and still have the same issues.  I have rebooted the mini-box and that did not help either.  TV works fine.