Model not found error only on my account

[sokail]

Model not found error message

I opened up a chat that I had used about a month ago to create an Excel macro. I wanted to make a couple of modifications to that macro. But after reopening that chat, everything I enter gets a “Model not found” error. [A notification with a red warning icon displays "Model not found," alongside a "Retry" button and options for copying, thumbs up, and thumbs down feedback. (Captioned by AI)] What is this error and what can I do about it?

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