Does ATS optimization with ChatGPT actually work?

I tried using ChatGPT to optimize my resume for a job. I pasted the job description, asked it to extract keywords and adjust my CV for ATS, and everything looked really aligned. Then I applied through Workday around midnight… and got rejected the next morning. It honestly feels automatic.

Now I’m confused. Does ATS optimization with ChatGPT actually work, or are companies filtering based on other things? Maybe Workday is rejecting based on some hidden criteria or questions?