ChatGPT transform & replace selection not working with custom API

Aloha!
This is a simple problem. I have created and inserted a secret key from openAI hoping to use gpt-4. But when I use it, I get a "(null)" response when attempting to trigger the shortcut. For example, I have highlighted the text: "what is the capitol of Vermont?" and it responds "(null)", inserting the response after the selected text.

What is the capitol of Vermont?

(null)

Don't know what else I can change to fix this.
Help please! thank you!

which version of BTT are you running? (there was a recent fix related to custom models)

Let's see... 4.361 (43610). Just updated. And I'll reboot the computer now too. We'll see if one of those things works.

[later]
Nope. Still giving me (null).
Thanks for your help, @Andreas_Hegenberg.