It seems the GPT-4 with browsing (GPT-4o) feature is either disabled or temporarily unavailable. You might be selecting the model correctly, but it's defaulting to regular GPT-4, which doesn't have internet access.

Try:

Logging out and back in. Clearing your browser cache. Checking OpenAI status for updates. Contacting OpenAI support for clarification. If browsing is down, responses will be immediate since the model isn't fetching real-time data.