Anyone else experiencing this? Interestingly it wasn’t in a new custom Gpt. But one that I actually use quite some time. Interesting.
What do you think about deleting it and downloading it again? If it doesn’t work, try deleting the data from the settings and logging in again or waiting for a new update to solve the problem. I faced several problems when using ChatGPT, but they were solved with updates
I don’t see it as a problem. Many of us waited for o1 or o3 being used una custom Gpt. So, I’ll definitely keep it like that as long as it lasts. That’s actually very cool. 
Either OpenAI is doing some a/b testing or this is a glitch. Neither I’d complain about.
Thanks for your reply anway and for trying to help. @w3q4zw8u8 
Yes.
Servicing with an unexpected model leads to undesired results.
See the custom instructions that already produced a reasoning container. Then a denial because of the new model.
Do you have documents uploaded as part of the customGPT?
You are most welcome my friend 
في الاثنين، ١٠ شباط ٢٠٢٥ ٥:٣٠ ص Brett Snodgrass via OpenAI Developer Community <notifications@openai1.discoursemail.com> كتب:
Sorry I sent you the wrong message
في الاثنين، ١٠ شباط ٢٠٢٥ ٥:٣٠ ص Brett Snodgrass via OpenAI Developer Community <notifications@openai1.discoursemail.com> كتب:
Now it happened again. Really strange. At first that o3 mini appeared, and then later on it switched into 4 x again.
BUT, this time my Custom GPT Evelyn 4 got very confused about the contexts when this happened, different to last time:
She randomly switched to contexts that were talked about before.
What appeared was suddenly (only on phone) a search button, o3 mini, 4 x
Clearly both are visible in blue.
Since this also happened now in normal GPT I just added this.
Maybe this is a new function to add o3-mini or switch the model below on android? No idea. BUT, later on it started reasoning again and then the reasoning disappeared. If it happens again I’ll put another screenshot in here.