SOLVED - Can’t get Agent mode to run in any project

Struggled with the same issue. Don’t really know whether that is an universal fix for everyone but at least I could somewhat use agent mode. Try launching agent mode from mobile app. There it successfully used web search after I submitted my prompt and started working. Then I could go back to ChatGPT website and open the same session where I sent my prompt. The only caveat was that in my case I couldn’t control virtual browser but I don’t think that’s a big deal. I hope this will be useful for someone.