I have two comcast.net accounts.
#! issue: The second account has not been updated when I try to access it from My Xfinity on my laptop since 10/31/2017! I can pull it up, updated, on both my Android smartphone as well as my tablet. They are configured as imap not POP.
#2 issue: That being the case, I should be able to sync deleted emails, etc from all of my devices too. Not the case. If I delete from my cell phone they are also deleted from my tablet and vice versa but never from MY XFINITY on my laptop???
On the laptop, are you using only the webmail interface and a browser? Or do you have the account enabled in a desktop client like Outlook or Thunderbird?