Question: Why did the Chofetz Chaim not make a blessing in the middle of a meal when he ate bread for kamput in his later years but he poskined in the Mishna Berura (177:1:4) that one should make a blessing on kamput even in the middle of a meal where you had washed on bread?
A. The Mishna Berura there says that anything part of the meal, meaning that it’s used to eat a normal meal with, main and sides, like meat, fish, eggs, vegetables, cheese, etc. things that also enhance the bread, all don’t need an extra blessing once the blessing on the bread is said at the beginning of the meal. However, add ons, for example any fruit brought in the beginning of the meal or dessert (which is not a mezonos, made out of grains) would require their own blessing. Kamput, cooked fruit, is listed there as an example of something which is used as an appetizer or a dessert which needs its own blessing.
B. The Sefer Teshuvos ViHanhagos (1:177) brings testimony that the Chofetz Chaim, the author of the Mishna Berura commentary on Shulchan Aruch, that he himself did not say a blessing on kamput and in fact other gedolim would first say a blessing on raw fruit during the meal and then ate the kamput, to exempt the kamput, in doubt.
Answer: See Dirshu (10) the reason why the Chofetz Chaim did not say a blessing on the kamput towards the end of his life is because that was part of his main meal, not a dessert or appetizer.