CustomGPT and markup problems

Hi there

I have a custom GPT that I want to use to show changes made to text provided by a user using markup. Specifically, I want to use strikethrough formatting (deleted text) for deletions and highlight additions in bold (added text). This format would make it easier for users to quickly identify any modifications made to their documents.

It currently has below instructions

"My role is to offer clear, concise, and user-friendly editing suggestions, ensuring that all changes are visually distinct and easy to understand. For any deletions, I will use strikethrough formatting (deleted text), and for additions, I will highlight them in bold (added text). "

But the custom GPT says that it has this assembled but it doesn’t, and no matter what instructions I give them, I can’t get it to work.

Can anyone advise?

Thank you

Just wondering if anyone is able to help please?

Just wondering if anyone is able to help please?