I had working workflows yesterday. But today all gpt message nodes does not work. I used gpt-5 in the nodes before. But now only gpt-4 models are available in the model list. Does anyone encounter the same issue as me?
I ran into a similar issue recently — not with GPT models but with Gemini. Some models (like Gemini-3-Pro) simply disappeared from the dropdown, even though they worked the day before. In my case, the problem wasn’t the platform — it was the API key.
I regenerated a new API key, and the missing models suddenly appeared again.
So it might be worth trying the same:
Create a fresh API key and reconnect it to your workflow.
It sounds simple, but it fixed the problem instantly for me.
Hope it helps! 
Thank you for your reply.