Using Xfinity TV, at the URL "https://xtv.comcast.net/recordings" - the only recordings listed are those initiated from the PC. Interestingly, I can see the most recently watched On Demand shows, and I can see recently deleted recordings, both of which were through my Xfinity set-top box. But shows that list on the set-top box as "Recordings" don't appear in the "Recordings" on my PC.
Clearly I am logged in, since I'm seeing recently watched and recently deleted stuff from the set-top. Also, the recording I initiated from my PC does appear in "Recordings" on the set-tops as well as on the PC.
It is ONLY recordings from the X1 DVR set-top unit that are NOT appearing on the PC website page "https://xtv.comcast.net/recordings" on a Windows PC. I tried both Internet Explorer and Chrome: both give the same problem. Tried on two different PCs. Same problem. Checked on my Android 4.2.2 tablet with the Xfinity app. Same problem.