GPT-5.5 thinking silently routed to 5.4 for 8 days

Welcome to the forum!

I see that you have contacted support , but I was curious about this myself. I know that the way models are selected changes frequently, so one of the better places to check is the OpenAI ChatGPT FAQ pages.

This topic came up in my search, although it left me with even more questions.

GPT-5.5 in ChatGPT

Since I could find no definitive answer, curious to hear what support notes.

Thanks for raising the issue here.