Why does using Customize ChatGPT prevent image generation?

Why does using Customize ChatGPT prevent plus customers from image generation? I recently had to cancel my subscription to chatgpt plus because it would not generate an image for me, when I asked why it said unspecified error which explains absolutely nothing. So I researched the issue on my own, and it turns out that if you have Customize ChatGPT toggled it can prevent images from being generated, why isn’t the company transparent about this?

I am a writer and needed a image of an original character based off of the story I am writing.