It happens over and over. Remote will not change channels. Only works on sound and on and off. Have spent 2 1/2 hrs on tel. with agent only to say I need a new remote - nonsense. If I wait a few hrs. or a day, it works again on its own.
you didn't say which remote you have. if it is an xr11 press setup until the remote's LED changes color then type in 987 - try channel change. working? then RF pair the remote again by pressing setup for LED change of color like before then press the Xfinity button.