Over the last week I have a couple of my feed either break or disappear. Not sure what is going on. Wanted you to know. Thanks.
I have the same problem. My Lifehaker feed has disappeared and I cannot add it back.
I just committed a fix for some other feeds that had an issue with duplicates.
Also fixed Lifehacker. You should now be subscribed to it again. If not, try adding it. I switched it over to the VIP feed, which includes full text.