So a lot of colleagues and friends of mine are experiencing the same issue. As of last week the "@" functionality to bring in a Custom GPT into a Custom GPT conversation thread does not seem to be working any longer. Anyone with a Teams account still have this function, but it seems it is no longer working for the Plus subscribers. I am in an a global AI community and some have this function still and some don't so it sounds like a bug issue. Please investigate as my entire Custom GPT build strategy is developed on the basis that having this "@" function working. I am based in London, UK and use an apple mac and Chrome browswer. Thank you.