When I navigate to https://docs.microsoft.com/en-us/users/<USER>/activity , I would always see list of my activities like questions I answered. However, today I observed like it showing I have been answered question from 4 days ago while I answered questions and add comments yesterday too. Even when I answered or add comments to a number of posts, it only shows one of them. Therefore, I believe there is a bug in displaying the most current activities (comment, answers, ...) and for some reason some of them won't be list down.