Cannot access/manage second phone landline when logged into account

I have 2 Comcast landlines (no mobile lines) and I cannot access the second line to manage, view call history, etc. while using the Xfinity app or logged into the website. I used to be able to switch between both phone numbers to view or manage calls and voice mails, but no more. I've spoken with Comcast reps several times and mostly they transfer me between departments without a resolution. All the reps agree that I have 2 phone lines, however they cannot offer a solution about online access to both. I am paying for full features of 2 phone lines and expect to be able see both when logged into my account.