The Great Dumpling Disaster

So this past wednesday was Nancy's (aka Nana's) birthday and I thought it would be nice to cook dinner for everyone. I know she likes my salad bar setup and chicken and dumplings and I've made that recipe so many times that I know it works. Or so I thought. So we have eight adults and six kids over for dinner and I'm running a little behind but not too bad. Got the salad bar up so everyone can make salads and wait for the dumplings. Got the dough made, got it all balled up and pinched off into the broth. Wait about ten minutes then add the chicken and egg back in the pot. Wait another five or ten minutes and test a dumpling just to be sure they are done before I tell everyone to grab a bowl. OMG! They are pure flour in the middle. I'm talking bite it open and loose flour falls all over your mouth. What in the world???? So I cook and cook and cook .... add water and cook some more ... I'm talking these things boiled for over an hour, if not closer to two. And they still were not cooked. I have never had this happen and I just don't understand it. I was ready to order pizza but everyone said they would eat them anyone. They ended up cutting the dumplings in half and let them absorb some juice. This was the strangest incident I think I have ever had in the kitchen. The recipe that I always use calls for self-rising flour which I never have on hand so I add in the salt and baking powder to make it self-rising. Well this time I happened to have a bag that we bought for something else and didn't use. This is the only difference between this night and the probably twenty other times I've made this recipe. And of course this would happen when I have a house full of people to feed. I really just don't understand it. Could the flour be bad in some way? Has anyone ever had an experience like this before? I totally puzzled.