You're right it does work when I stay in the same window, I think it's as I'm opening a new tab that I'm getting mixed up with. The agent often provides a link to a document as part of the answer and I'll open a new tab to look into that, but the agent disappears and I couldn't find a way to get it back on the new tab. However, I've now realised the star icon on the top right does make the docked agent open/close, which is great, so I can just click the 3 dots to find the chat again. In short - ignore me it's all perfect