Are there limited favorite channels in the Xfinity streaming app?

I have been working to assign my favorite channels, so I can use the favorite channel list and not "all channels".  However, I have noticed that some channels that were assigned as favorites are now not favorites.  They are the ones I use the most, so I would not have removed them from my list - ABC, NBC, CBS are a few.  I have noticed that the ones I recently assigned as favorites are now favorites.   Any idea why this would be?  I have also noted that some channels are duplicated way up in the 1000+ numbers.  What is the purpose of having these duplicates.  Any help would be appreciated.