Sorry to hear it. However, we don't have a "sorting by activity feature" It looks like you mixed something up. The available sorting options in the video feed are by date, video length, and most popular.

EDIT: Can you send a screenshot with the "Sort by activity" button? We don't have it in the UI. If you mean the list of subscriptions instead of video feed, currently we support Date Published, A-Z, and custom. Other options were discontinued years ago due to YouTube restrictions.