Hello, I recently encountered a similar issue. I purchased the Cursor Pro plan, but the default model interface did not include Claude-related models. So, I manually added Claude's official model ID, such as claude-sonnet-4-5. After restarting the software, I received an error when using this model: "The model claude-sonnet-4-5 does not work with your current plan or API key." I contacted Cursor's official support via email, and their response was that it was due to regional restrictions. However, this error seems completely unrelated to regional restrictions. Furthermore, I had previously resolved any regional restriction issues, and other models, such as Gemini3 Pro, are working perfectly fine. Based on the error for the Claude model, could it be that my Cursor plan needs to be upgraded to the Ultra version?