Quick note, if you are trying to open the GPT on the phone it may be defaulting to the ChatGPT app where custom GPTs are not available yet. Try to open the GPT link via browser where you first login to your ChatGPT+ account if you want to use the GPT on the phone. Let me know if you have any issues. Here is theGPT URL: https://chat.openai.com/g/g-Ezvt5oGuN-master-design-thinker