xr11 & xr15 remote programming

We have a LG 55 " flat screen tv approx 10 years old. We have the x1 tv platform and for the past  2-3 weeks  we could not use the volume control on the xr11 remote ... I paired it with the tv probably 20 times and it would work for a couple of days and the go back to the same problem. Every other key on the remote except those associated with the volume (volume & power) worked as it should ... so today I exchanged the xr11 remote for a xr15 remote with the local xFinity office. I paired it with the tv and still got the same result .. I then went back to my "office" and got the other xr11 with the system back there and again got the same result.  I am beginning to belleve the problem is with either the tv or the DVR box. Anyone  else had this problem ??