click the tv tab top of this page, then on the next page click the wheel on the bottom right. go to cable boxes and devices and see what's listed there. If you got new boxes from comcast they need to be added correctly to your account and the old boxes removed. Only comcast can do that. Also in your box menu see if you see remote access set up there, If you do you there is a code there for you to use. you can also delete the set up if its there to start over with the resynch from the app. the synch can take 24-48 hours and usually does.
I tried to set up the DVR manager and right after this, my DVR stopped working entirely. I have had my cable boxes swapped out, the boxes "reset", etc. My DVR still does not work with the new boxes. When I try to manager my DVR devices i get a message saying that a sync is in progess, yet I have not tried to sync my new boxes to the DVR manager. Is there any way to have the DVR manager "forget" my old boxes entirely?