Xfinity Stream suddenly missing local channels such as ABC and NBC on an Amazon Fire TV

My Xfinity Stream app suddenly has lost access to local channels such as ABC and NBC ( maybe more ) on an Amazon Fire TV.  These channels have always been available on this TV before but now are gone for some reason.  If I try to click on them, I get a message "Please connect to your in-home WiFi".  This only happens on this one TV.  The local channels all come up fine on the app on my other TV's, my PC, and Android phone.  I have uninstalled and reinstalled the app to no avail.  I cannot understand why this is suddenly happening.  Has anyone else experienced this or have any ideas?